Find three solutions of the equation.
y = –2x
a.(0, 0), (3, –8), (–2, –4)
b.(1, –2), (0, 0), (–1, 1)
c.(–2, 4), (1, –2), (0, 0)
d.(–2, 4), (1, –2), (2, –3)

Since you are only given one function with two variables, you can't solve the problem. So, you do trial and error for all points. 

a.) 
(0,0): 0 = -2(0) => 0 = 0 (true)
(3,-8): -8 = -2(3) => -8 = -6 (false, move to the next choice)

b.)
(1,-2): -2 = -2(1) => -2 = -2  (true)
(0,0): true
(-1,1): 1 = -2(-1) => 1=2 (false)

c.)
(-2,4): 4 = -2(-2) => 4 = 4 (true)
(1,-2): true
(0,0): true

Thus, the answer is C.

Abcd stupid son of a bitxh