f(x) = 4 -2x^2
First we need to find f(6)
f(6) = 4 - 2( 6) ^2 = 4 - 2(36) = 4 - 72 = -68
Then we need to find
f(-6) = 4 - 2( -6) ^2 = 4 -2( 36) = 4 - 72 = -68
Now we find the average or mean slope
The mean slope is zero
Now f'(c) must equal 0
The derivative is -4x and evaluated at c
-4c
This must be equal to 0
-4c =0
Solving for c
c=0