If xk + yk = ak (where a, k > 0) and dydx + (yx)13 = 0, then the value of k is:

Let f(x) = tan-1(x1/3 + a1/31 - x1/3a1/3), then f'(x) equals:

Which statement about the derivative of a constant function is correct?

Which of the following correctly represents the second derivative y2 if x2 + y2 = r2?