please write every answer with question number

Question 18 Use the substitution x - 3 tan(0) to evaluate the indefinite integral 26dx 2 Vx2 + 9 +CQuestion 19 - 16 Evaluate the integral: da x2 Vx2 + 64 (A) Which trig substitution is correct for this integral? Ox - 8 sin(0) Or = 8 tan(0) Or - - 16 sec(0) Ox = 64 sin(0) Ox = 64 tan(0) Ox = 64 sec(0) (B) Which integral do you obtain after substituting for a and simplifying? Note: to enter 0, type the word theta. do (C) What is the value of the above integral in terms of 0? C (D) What is the value of the original integral in terms of x? C