# How do you find the slope and y intercept for x=4?

$x = 4$ represents a vertical line passing through $x = 4$.
1] It is not possible to define its slope $m$;
in fact $m = \frac{\Delta y}{\Delta x}$ but $\Delta x = 4 - 4 = 0$ so you get a division by zero!
2] Being a vertical line through $x = 4$ it will never cross the $y$ axis!