12 Problem 4: [12.5 pts] Harper needs to evaluate the integral x2 - 9 dx but is unsure how to do so. 12 A. [5 pts] Use the substitution x = 3 sec(0) to show Harper how to evaluate 72 - 9 dx. Simplify your final answer. Hint: You may use the formulas derived in class for / sec(0) do, / csc(0) de, / tan(0) do, or / cot(0) de should one of them arise. You do not need to derive any of these results