Question

A line passes through the points (4,-4) and (8,12). What is the y-intercept of the line ?

Answer 1

$\frac{y2-y1}{x2-x1}= \frac{y-y1}{x-x1} = \frac{12-(-4)}{8-4}= \frac{y-(-4)}{x-4}$
$\frac{16}{4}= \frac{y-(-4)}{x-4 } = 4(x-4)=(y+4)$
$4x-16=y+4$
$4x=y+4+16$
$4x=y+20$
$y=4x-20$