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What is a rational expression?It is a ratio of two polynomial expressions, like this:
We will begin by reducing fractions
Now we will reduce Polynomials
Simplify rational expressions means that we could not reduce or factor anything else out of the expression.
Simplify, Multiply, and DivideRational Expressions
Now let’s reduce Polynomials
When dividing polynomials, they are called ____rational expressions____
There are two steps for reducing/simplifying rational expressions.
Step 1. ___Factor the numerator and denominator___
Step 2. _____Reduce/Cancel like terms.
Simplify
Look for common factors.
Simplify.Answer:
Under what conditions is this expression undefined?
A rational expression is undefined if the denominator equals zero. To find out when this expression is undefined, completely factor the denominator.
Answer: The values that would make the denominator equal to 0 are –7,
3, and –3. So the expression is undefined at y = –7, y = 3, and y = –3. These values are called excluded values.
a. Simplify
b. Under what conditions is this expression undefined?
Answer:
Answer: undefined for x = –5, x = 4, x = –4
Multiple-Choice Test Item
For what values of p is undefined?
A 5 B –3, 5 C 3, –5 D 5, 1, –3
Read the Test ItemYou want to determine which values of p make the denominator equal to 0.
Solve the Test ItemLook at the possible answers. Notice that the p term and the constant term are both negative, so there will be one positive solution and one negative solution. Therefore, you can eliminate choices A and D. Factor the denominator.
Factor the denominator.
Solve each equation.
Answer: B
Zero Product Propertyor
Multiple-Choice Test Item
For what values of p is undefined?
A –5, –3, –2 B –5 C 5 D –5, –3
Answer: D
Simplify
Simplify.Answer: or –a
Simplify
Answer: –x
Simplify
Answer: Simplify.
Simplify
Answer: Simplify.
Simplify each expression.
a.
b.
Answer:
Answer:
Simplify
Answer: Simplify.
Simplify
Answer:
Simplify
Answer: Simplify.
Simplify
Simplify.Answer:
Stopped here after day 1
Answer: 1
Simplify each expression.
a.
b.
Answer:
Simplify
Express as adivision expression.
Multiply by thereciprocal of divisor.
Factor.
1 1 –1
1 1 1
Simplify.Answer:
Simplify
Answer:
Example 1 LCM of Monomials
Example 2 LCM of Polynomials
Example 3 Monomial Denominators
Example 4 Polynomial Denominators
Example 5 Simplify Complex Fractions
Example 6 Use a Complex Fraction to Solve a Problem
Find the LCM of 15a2bc3, 16b5c2, and 20a3c6.
Factor the firstmonomial.
Factor the secondmonomial.
Factor the thirdmonomial.
Use each factor the greatest number of times it appears as a factor and simplify.
Answer:
Find the LCM of 6x2zy3, 9x3y2z2, and 4x2z.
Answer: 36x3y3z2
Find the LCM of x3 – x2 – 2x and x2 – 4x + 4.
Factor the first polynomial.
Factor the second polynomial.
Answer: Use each factor the greatest number of times it appears as a factor.
Find the LCM of x3 + 2x2 – 3x and x2 + 6x + 9.
Answer:
Simplify
The LCD is 42a2b2. Find equivalent fractions that have this denominator.
Simplify each numerator and denominator.
Add the numerators.Answer:
Simplify
Answer:
Simplify
Factor the denominators.
The LCD is6(x – 5).
Subtract the numerators.
DistributiveProperty
Combine liketerms.
Simplify.
1
1
Simplify.Answer:
Simplify
Answer:
Simplify
The LCD of the numerator is ab. The LCD of the denominator is b.
Simplify the numerator and denominator.
Write as a divisionexpression.
Multiply by the reciprocal of the divisor.
1
1
Simplify.Answer:
Simplify
Answer:
Coordinate Geometry Find the slope of the line that
passes through and
Definition of slope
The LCD of the numerator is 3k. The LCD of the denominator is 2k.
Write as a division expression.
Simplify.
Answer: The slope is
Coordinate Geometry Find the slope of the line that
passes through and
Answer:
Example 1 Vertical Asymptotes and Point Discontinuity
Example 2 Graph with a Vertical Asymptote
Example 3 Graph with Point Discontinuity
Example 4 Use Graphs of Rational Functions
Determine the equations of any vertical asymptotes and the values of
x for any holes in the graph of
First factor the numerator and denominator of the rational expression.
Answer: The function is undefined for x = –2 and –3.
Since x = –3 is a vertical
asymptote and x = –2 is a hole in the graph.
1
1
Determine the equations of any vertical asymptotes and the values of
x for any holes in the graph of
Answer: vertical asymptote: x = –5; hole: x = –3
Answer:Graph
The function is undefined for
x = –1. Since is in its
simplest form, x = –1 is a vertical asymptote. Draw the vertical asymptote.
Make a table of values.
x f (x)
–4 1.33
–3 1.5
–2 2
0 0
1 0.5
2 0.67
3 0.75
Answer:
Plot the points and draw the graph.
As |x| increases, it appears that the
y values of the function get closer and closer to 1. The line with
the equation f (x) = 1 is a
horizontal asymptote of
the function.
Answer:
Graph
Answer:
Graph
Notice that or Therefore,
the graph of is the graph of
with a hole at
Answer:
Graph
Answer:
Transportation A train travels at one velocity V1 for a given amount of
time t1 and then another velocity V2 for a different amount of time t2. The average
velocity is given by
Let t1 be the independent variable and let V be the dependent
variable. Draw the graph if V1 = 50 miles per hour, V2 = 30 miles
per hour, and t2 = 1 hour.
Answer:
The function is
The vertical asymptote is Graph the vertical
asymptote and the function. Notice that the horizontal
asymptote is
What is the V-intercept of the graph?
Answer: The V-intercept
is 30.
What values of t1 and V are meaningful in the context of the problem?
Answer: In the problem context, time and velocity are positive values. Therefore, positive values
of t1 and V values between 30 and 60 are meaningful.
Transportation A train travels at one velocity V1 for a given amount of
time t1 and then another velocity V2 for a different amount of time t2. The average
velocity is given by
a. Let t1 be the independent variable and let V be the
dependent variable. Draw the graph if V1 = 60 miles
per hour, V2 = 30 miles per hour, and t2 = 1 hour.
Answer:
b. What is the V-intercept of the graph?
c. What values of t1 and V are
meaningful in the context of
the problem?
Answer: The V-intercept is 30.
Answer: t1 is positive and V is between 30
and 60.