Module 4 Topic 3

Writing Linear Equations

The equation for slope-intercept form is

m is the slopeslope measures the steepness of the linem=-4/2=-2

b is the y-interceptb is where the line crosses the y-axis.

bmxy

-4

2

Write the equation of the line that has a slope of -4 and y-intercept of 5.

bmxy

54 xy

We use Point-Slope form, when we are given: a point and a slope!

Write the equation of the line that passes

through (-3,5) and has a slope of 2.

What are we given? We are given the

slope is 2!

AND…we are given a point

(-3,5).

Final Answer

Write the equation of the line that passes through

(-3,5) and (-1,9) .

What are we given? We are given 2

points, but no slope!

Can we find the slope? Do

we have enough info?

Yes, we can use…

22

4

)3(1

59

m

Write the equation of the line that passes through

(-3,5) and (-1,9) .

Now that we know that the slope is 2, we can use either point to find the

equation of the line.

Summary1.When given the slope and y-intercept: y=mx+b.2.When given 1 point and the slope, do point slope: y – y1=m(x-x1).3.When given 2 points, and no slope, one must find the slope (m=y2-y1 over x2-x1), then use either point for the point slope form.

Now proceed to Mastery Assignments!