(3) Now consider the integral 2 81:2 I = dt. /. .2 (a) Change variables using the substitution u = t2. Explain why that won't help with solving this integral. (b) It turns out that you cannot express that integral in terms of functions you learned so far. So our best bet is to approximate it using Riemann sums. t2 e First, let's try to understand the function we are integrating. Find the derivative of the function at) 2 t2 and decided whether this function is increasing or decreasing on the interval [1, 2]. (c) Use your answer in (b) to nd the worst overestimate and the worst underestimate for our integral I using 6 rectangles of equal base length. What is the average between the worst overestimate and the worst underestimate? Feel free to use a calculator for the evaluations here. Work with 5 decimal places and express your final answer using 4 decimal places (that is, 4 numbers after the point) (e) Estimate our integral I using 6 rectangles of equal base length but now with midpoints as sample points. Feel free to use a calculator for the evaluations here. Work with 5 decimal places and express your nal answer using 4 decimal places (that is, 4 numbers after the point)