# How to find the y-intercept given A=(-1,2) B=(-2,8)?

May 9, 2015

One method would be to determine an equation for the line through the points $A = \left(- 1 , 2\right)$ and $B = \left(- 2 , 8\right)$
and then substitute $x = 0$ in the equation.

$\frac{{\Delta}_{y}}{{\Delta}_{x}} = \frac{y - 2}{x + 1} = \frac{8 - 2}{- 2 + 1}$

$\left(y - 2\right) = \left(- 6\right) \left(x + 1\right)$

$y = - 6 x - 4$

when $x = 0$ (that is, along the y-axis)
$y = - 4$

The y-intercept is $\left(- 4\right)$