CPM Homework Help : CCA Problem 2-91

Find the equation of the line that goes through the points $(-15,70)$ and $(5,10)$ .

Hint:

One strategy is to graph the two points and make a slope triangle to find the slope of the line.

Step 1:

Use the slope triangle to find the slope of this line.

$m=\frac{\Delta y}{\Delta x}=\frac{-60}{20}$

Step 2:

Substitute a pair of coordinates for $x$ and $y$ and the slope to solve for $b$ .
$y=mx+b$
$10=-3\left(5\right)+b$
$10=-15+b$
$25=b$

More Help:

Substitute the values found for $m$ and $b$ into the equation of the line.

Use the eTool below to help solve the problem.
Click the link at right for the full version of the eTool: 2-91 HW eTool