Find an approximation to the integral. (x²4x) dx using a Riemann sum with right endpoints and n-8. Re 1/4 x X (b) If fis Integrable on [a, b], then -5.8125 Need Help? Read It on [°^x) dx = lim na 1x) Ax, where Ax=5 and x, a +/Ax. Use this to evaluate - [ (x² - 4x) dx. 7-1 b-a n