Question

what is the y-intercept of the line given by the equation ?
y=8x + 7

Answer 1

compare with y=mx+c
c=y-intercept

Answer 2

put x=0 and y=7

Answer 3

Graph it on your calculator and look at the picture, you'll see:



Where is the y-intercept? It's where your line intersects the y-axis. Where is that? Well, you can see that it happens when x=0, so you can plug that into your formula to find your y-axis.

Knowing this and the standard form y=mx+b, every time you want to know the y-axis you can see that the "b" term is going to be your y-intercept every single time because of this!