Question

What is the equation of a line that passes through (0,-2) and has a slope of 0

Answer 1

If we then plug in the slope and y intercept into the slope-intercept formula of y=mb+b where m= the slope the b= the y intercept, then 
y=mx+b becomes
y=0x+(−2) which simplifies to y=−2

Answer 2

A slope of 0....this means that u have a horizontal line...which is represented by y = a number....with that number being the y coordinate of ur point (0,-2).
Therefore, ur equation is : y = -2

learn this, it helps...
HOY -- horizontal line, 0 slope, represented by y = a number
VUX -- vertical line, undefined slope, represented by x = a number