Rectangle areas are found by calculatingheight width.The width of each rectangle equalsxand the height of each rectangle is given by the function value at the right-hand side of the rectangle.So we must calculateR4=4f(xi)x =f(x1)+ f(x2)+ f(x3)+ f(x4)xi =1,wherex1, x2, x3, x4represent the right-hand endpoints of four equal subintervals of0,2.Since we wish to estimate the area over the interval0,2using 4 rectangles of equal widths, then each rectangle will have widthx =