Answer: 1 and -3
Explanation:
You plug in the X value and then solve.
So the first one is plugging in -1, plugging in 2, and then adding them together.
f(-1) = 2*(-1)^2 - (-1) - 4 = -1
f(2) = 2*(2)^2 - 2 - 4 = 2
f(-1)+f(2) = -1+2 = 1
while f(-1) - f(2) = -1 - 2 = -3