26. Incorrect. The answer is false, not true. To find the
optimal point set the first derivative of f'(x) = 0, or f'(x) = 2x - 12 = 0. From this x_{0} = 6. To determine whether the
optimal point is a relative/global maximum of minimum or neither, check the
sign of the second derivative evaluated at the optimal point: f"(x) = 2
for all values of x, therefore, x_{0} is a global minimum.