Hi, For this integration by substitution problem, I am not sure whether I should: 1. simplify the problem first, then select U, find the derivative of U, then integrate or 2. use the product rule first (on the upper part of the equation), then select U, then find the derivative of U, then integrate, or 3. if I could just cancel like terms first, and be left with cos to integrate 1. The problem statement, all variables and given/known data Evaluate the indefinite integral 2. Relevant equations integral of cos * (square root of t) / (square root of t) dt 3. The attempt at a solution integral of cos * (square root of t) / (square root of t) dt integral of [cos t^(1/2)] / t^(1/2) dt let U = cos t ^ 1/2 du = 1/2 (sin t 3/2) / (t 3/2) Now I am really lost! What should I do?