Which rule matches the function graphed in the image?

a: y = -2x
b: y = x + 4
c: y = 2x
d: y = x - 4

show work? !

How do you find the correct equation? Follow these steps.

First, plug 0 in for X and solve for Y . Does the y value match what is on the graph? 0 in this case?

a. 0 = -2(0) True - This could be an answer
b. 0 = 0 + 4 False - This cannot be an answer
c. 0 = 2(0) True - This could be an answer
d. 0 = 0 - 4 False - This cannot be an answer

Now we are down to 2 possible answers A and C. Now take another point on the line, say x=-2 and repeat, does the answer match what is on the graph? (4). 

a. 4 = -2(-2) True
c. 4 = 2(-2) False

As only A matches, A must be the answer. With graphing problems, when you have to find the correct equation, always choose X=0 as the first point (assuming it has a Y value) and eliminate answers. I hope this helps.