Consider the indefinite integral fx. x + 9 dx This can be transformed into a basic integral by letting a. u=[answer1] b. du = ____dx [answer2] c. Performing the substitution yields the integral S--- du [answer3] Evaluate the integral 15 Sx (x8-4) 5 dx by making the appropriate substitution: [answer1] U 15 fx(x8-4) 5 dx + C [answer2]