11:28 71 = 4 rectangles, using the right corner of each rectangle. The area of each rectangle is f(a:)A:c . In this case, x is the right endpoint of each subinterval, and f(:c) is the corresponding height, and A33 is the width of each rectangle. Then we use the Sum command to add the area of each rectangle (using i from 1 to 4) NSum[f[x[i,0,3,4]]*delta[0,3,4],{i,1,4}] Then press Step 7: We will make one more function, 'r(n) that will approximate the area for any given number of rectangles. r[n_]: =NSum[f[x[i,0,3,n]]*delta[0,3,n], {i,1,n}] Then press ? Question The answer is close to 16 Hint 1 Based on the above practice problem, when n = 8, what is the approximated area? Question Help: 8 Message instructor Submit Question ? Question Hint 1 For the first five positive integers, find the sum of the square of each integer multiplied by four. 4.12+4.22+4.32+4.42+4.52 Question Help: 8 Message instructor Submit