# What is the slope of the line passing through the following points: (-9,1) , (-4, -2)?

Dec 22, 2015

$- \frac{3}{5}$

#### Explanation:

General form of a straight line is $y = a x + b$
$\implies 1 = - 9 a + b$ and $- 2 = - 4 a + b$
$b = 1 + 9 a$
$- 2 = - 4 a + \left(1 + 9 a\right)$
$- 3 = 5 a$
$a = - \frac{3}{5}$
$b = 1 + 9 \cdot \left(- \frac{3}{5}\right) = 1 - \frac{27}{5} = - \frac{22}{5}$
$5 y = - 3 x - 22$

The slope is given by a