18. Incorrect. The answer is false, not true. dy/dx = (1/3)*(-3)*x^{(1/3 – 1)} = -1*x^{-2/3} = -1/x^{2/3}_{. }dx/dy = 1/(dy/dx) = 1/(-1/x^{2/3}) = - x^{2/3}. _{}