Find the sum of the largest and smallest values of the function y = x ^ 4-2x ^ 2-6 on the segment [-2; 2]

Find the derivative:
y ‘(x) = 4x ^ 3-4x;
Then we find the value of the derivative at the ends of the segment and at x = 0:
For x = -2;
y ‘(- 2) = 4 * (- 8) + 8 = -24;
For x = 2;
y ‘(2) = 4 * 8 + 8 = 40;
For x = 0;
y ‘(0) = 0;
As a result:
Highest value = 40;
Lowest value = -24;
Amount = 40-24 = 16;
Answer: sum = 16.