$y=-2x+4$y=-2x+4

$\displaystyle y= \frac{1}{2}x$\displaystyle y= \frac{1}{2}x

$\displaystyle y=- \frac{1}{2}x+1$\displaystyle y=- \frac{1}{2}x+1

$y=2x-4$y=2x-4