# How do you find the slope of the line containing points with the coordinates (-4, -5) and (4, 4)?

Mar 19, 2018

$+ \frac{9}{8}$

#### Explanation:

You always read left to right on the x-axis (unless stated otherwise)

The left most $x$ is the -4

Set point 1 as ${P}_{1} \to \left({x}_{1} , {y}_{1}\right) = \left(- 4 , - 5\right)$

Set point 2 as ${P}_{2} \to \left({x}_{2} , {y}_{2}\right) = \left(4 , 4\right)$

Slope (gradient) is the change in up or down for a given amount of along.

If the change is down then the gradient is negative.
If the change is up then the gradient is positive.

Gradient is ${P}_{2} - {P}_{1} \to \left(\text{change in up or down")/("change in along}\right) = \frac{{y}_{2} - {y}_{1}}{{x}_{2} - {x}_{1}}$

Set gradient as $m = \frac{{y}_{2} - {y}_{1}}{{x}_{2} - {x}_{1}} = \frac{4 - \left(- 5\right)}{4 - \left(- 4\right)} = \frac{4 + 5}{4 + 4} = + \frac{9}{8}$