1. Consider the function f(x) = X^(4/3) +4x^(1/3) on the interval -8 ≤ x ≤ 8.
a. Find the coordinate of all points at which the tangent to the curve is a horizontal line.
b. Find the coordinate s of all points at which the tangent to the curve is a vertical line.
c. Find the coordinates of the points at which the absolute maximum and absolute minimum occur.