7. Find the derivative: * (x2x) 8. Sketch the graph. Use the left endpoints for Riemann sum to estimate the area under the curve. f(x) = x2 -1, on [2, 4] n= 4 9. An adult consumes an expresso containing 75 mg of caffeine. If the caffeine has a half- life of 5.5 hours, when will the amount of caffeine in her bloodstream equal 30 mg