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Equations That May be Reduced to Quadratics

5 4 equations that may be reduced to quadratics-x

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Page 1: 5 4 equations that may be reduced to quadratics-x

Equations That May be Reduced to Quadratics

Page 2: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method

Equations That May be Reduced to Quadratics

Page 3: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Page 4: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Page 5: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given ( xx – 1 )

2

– ( xx – 1 ) – 6

Page 6: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given

if we substitute y for

( xx – 1 )

2

– ( xx – 1 ) – 6

xx – 1

Page 7: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given

if we substitute y for

then the expression is y2 – y – 6.

( xx – 1 )

2

– ( xx – 1 ) – 6

xx – 1

Page 8: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given

if we substitute y for

then the expression is y2 – y – 6.

( xx – 1 )

2

– ( xx – 1 ) – 6

xx – 1

b. Given (x2 – 1)2 – 3(x2 – 1) + 2

Page 9: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given

if we substitute y for

then the expression is y2 – y – 6.

( xx – 1 )

2

– ( xx – 1 ) – 6

xx – 1

b. Given (x2 – 1)2 – 3(x2 – 1) + 2

if we substitute y for (x2 – 1)

Page 10: 5 4 equations that may be reduced to quadratics-x

In this section, we solve equations that may be reduced to

2nd degree equations by the substitution method and

fractional equations that reduce to 2nd degree equations

Equations That May be Reduced to Quadratics

Substitution Method

If a pattern is repeated many times in an expression, we may

substitute the pattern with a variable to make the equation

look simpler.

Example A.

a. Given

if we substitute y for

then the expression is y2 – y – 6.

( xx – 1 )

2

– ( xx – 1 ) – 6

xx – 1

b. Given (x2 – 1)2 – 3(x2 – 1) + 2

if we substitute y for (x2 – 1)

then the expression is y2 – 3y + 2.

Page 11: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

Equations That May be Reduced to Quadratics

Page 12: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

Equations That May be Reduced to Quadratics

Page 13: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

Page 14: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations.

Page 15: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution,

Page 16: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Page 17: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

Page 18: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

We substitute y = x2 so x4 = y2, the equation is

y2 – 5y – 14 = 0 (1st equation to solve)

Page 19: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

We substitute y = x2 so x4 = y2, the equation is

y2 – 5y – 14 = 0 (1st equation to solve)

(y – 7)(y + 2) = 0

y = 7, y = –2

Page 20: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

We substitute y = x2 so x4 = y2, the equation is

y2 – 5y – 14 = 0 (1st equation to solve)

(y – 7)(y + 2) = 0

y = 7, y = –2

To find x, since y = x2 , so 7 = x2 and –2 = x2

Page 21: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

We substitute y = x2 so x4 = y2, the equation is

y2 – 5y – 14 = 0 (1st equation to solve)

(y – 7)(y + 2) = 0

y = 7, y = –2

To find x, since y = x2 , so 7 = x2 and –2 = x2

(2nd equation to solve)

Page 22: 5 4 equations that may be reduced to quadratics-x

c. Given x4 – 5x2 – 14,

if we substitute y = x2 so x4 = y2,

then the expression is y2 – 5y – 14.

Equations That May be Reduced to Quadratics

To solve an equation via substitution, instead of solving one

difficult equation, we solve two easy equations. We first solve

the 2nd degree equations obtained after the substitution, than

put the answers back to the substituted pattern and solve

those equations.

Example B. Solve x4 – 5x2 – 14 = 0 for x.

We substitute y = x2 so x4 = y2, the equation is

y2 – 5y – 14 = 0 (1st equation to solve)

(y – 7)(y + 2) = 0

y = 7, y = –2

To find x, since y = x2 , so 7 = x2 and –2 = x2

(2nd equation to solve) ±7 = x ±i2 = x

Page 23: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

Equations That May be Reduced to Quadratics

Page 24: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

Equations That May be Reduced to Quadratics

Page 25: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

Equations That May be Reduced to Quadratics

Page 26: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 27: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 28: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x

3x – 3 = x

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 29: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x

3x – 3 = x

x = 3/2

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 30: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x –2(x – 1) = x

3x – 3 = x

x = 3/2

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 31: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x –2(x – 1) = x

3x – 3 = x –2x + 2 = x

x = 3/2

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 32: 5 4 equations that may be reduced to quadratics-x

Example C. Solve for x.

We substitute y = the equation is

y2 – y – 6 = 0 (1st equation to solve)

(y – 3)(y + 2) = 0

y = 3, y = –2

To find x, since y =

so 3 = and –2 = (2nd equation to solve)

3(x – 1) = x –2(x – 1) = x

3x – 3 = x –2x + 2 = x

x = 3/2 2/3 = x

( xx – 1 )

2– ( x

x – 1 ) – 6 = 0

xx – 1

xx – 1

xx – 1

xx – 1

Equations That May be Reduced to Quadratics

Page 33: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

Equations That May be Reduced to Quadratics

Page 34: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3

Equations That May be Reduced to Quadratics

Page 35: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2,

Equations That May be Reduced to Quadratics

Page 36: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

Equations That May be Reduced to Quadratics

Page 37: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

Equations That May be Reduced to Quadratics

Page 38: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

Equations That May be Reduced to Quadratics

Page 39: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve)

Equations That May be Reduced to Quadratics

Page 40: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3

Equations That May be Reduced to Quadratics

Page 41: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3

27/8 = x

Equations That May be Reduced to Quadratics

Page 42: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x

Equations That May be Reduced to Quadratics

Page 43: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x –8 = x

Equations That May be Reduced to Quadratics

Page 44: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x –8 = x

Equations That May be Reduced to Quadratics

Recall the steps below for solving a rational equation.

Page 45: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x –8 = x

Equations That May be Reduced to Quadratics

Recall the steps below for solving a rational equation.

I. Find the LCD.

Page 46: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x –8 = x

Equations That May be Reduced to Quadratics

Recall the steps below for solving a rational equation.

I. Find the LCD.

II. Multiply both sides by the LCD to get an equation without

fractions.

Page 47: 5 4 equations that may be reduced to quadratics-x

Example D. Solve 2x2/3 + x1/3 – 6 = 0 for x.

We substitute y =x1/3 so x2/3 = y2, the equation is

2y2 + y – 6 = 0 (1st equation to solve)

(2y – 3)(y + 2) = 0

y = 3/2, y = –2

To find x, use y = x1/3, so 3/2 = x1/3 and -2 = x1/3

(2nd equation to solve) (3/2)3 = (x1/3)3 (–2)3 = (x1/3)3

27/8 = x –8 = x

Equations That May be Reduced to Quadratics

Recall the steps below for solving a rational equation.

I. Find the LCD.

II. Multiply both sides by the LCD to get an equation without

fractions.

III. Solve the equation and check the answers, make sure it

doesn't make the denominator 0.

Page 48: 5 4 equations that may be reduced to quadratics-x

Example E. Solve x + 1x – 1

– 2 =3

x + 1

Equations That May be Reduced to Quadratics

Page 49: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

x + 1x – 1

– 2 =3

x + 1

Equations That May be Reduced to Quadratics

Page 50: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

Equations That May be Reduced to Quadratics

Page 51: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1)

Equations That May be Reduced to Quadratics

Page 52: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1)

Equations That May be Reduced to Quadratics

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Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 54: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 55: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 56: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x2 + 2x + 1 – 2x2 + 2 = 3x – 3

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

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Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x2 + 2x + 1 – 2x2 + 2 = 3x – 3

-x2 +2x + 3 = 3x – 3

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 58: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x2 + 2x + 1 – 2x2 + 2 = 3x – 3

-x2 +2x + 3 = 3x – 3

0 = x2 + x – 6

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 59: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x2 + 2x + 1 – 2x2 + 2 = 3x – 3

-x2 +2x + 3 = 3x – 3

0 = x2 + x – 6

0 = (x + 3)(x – 2)

x = –3 , x = 2

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 60: 5 4 equations that may be reduced to quadratics-x

Example E. Solve

The LCD is (x – 1)(x + 1), multiply the LCD to both sides,

(x – 1)(x + 1) [ ]

(x + 1) (x + 1) – 2(x – 1)(x + 1) = 3(x – 1)

x2 + 2x +1 – 2(x2 – 1) = 3x – 3

x2 + 2x + 1 – 2x2 + 2 = 3x – 3

-x2 +2x + 3 = 3x – 3

0 = x2 + x – 6

0 = (x + 3)(x – 2)

x = –3 , x = 2

Both solutions are good.

x + 1x – 1

– 2 =3

x + 1

x + 1x – 1

– 2 =3

x + 1

(x + 1) (x – 1)(x + 1) ( x – 1)

Equations That May be Reduced to Quadratics

Page 61: 5 4 equations that may be reduced to quadratics-x

Equations That May be Reduced to QuadraticsExercise A. Solve the following equations. Find the exact and

the approximate values. If the solution is not real, state so.

1. x4 – 5x2 + 4 = 0

3. 2x4 + x2 – 6 = 0

2. x4 – 13x2 + 36 = 0

4. 3x4 + x2 – 2 = 0

5. 2x4 + 3x2 – 2 = 0 6. 3x4 – 5x2 – 2 = 0

7. 2x6 + x3 – 6 = 0 8. 3x6 + x3 – 2 = 0

9. 2x6 + 3x3 – 2 = 0 10. 3x6 – 5x3 – 2 = 0

11. 2x + x1/2 – 6 = 0 12. 3x + x1/2 – 2 = 0

13. 2x + 3x1/2 – 2 = 0 14. 3x – 5x1/2 – 2 = 0

15. 2x –2/3 + x –1/3 – 6 = 0 16. 3x –2/3 + x – 1/3 – 2 = 0

17. 2x –2/3 + 3x – 1/3 – 2 = 0 18. 3x –2/3 – 5x – 1/3 – 2 = 0

19. 2 2 + – 6 = 02x – 3x + 1)(2x – 3

x + 1)(

20. 2 –2 + –1 – 6 = 0x + 1 )(2x – 3 2x – 3

x + 1)(