Please provide explanations for 1, 5, 9. Thank you. Readied the picture

= 29 29 ~ 2.9 ft/ sec as the rate at which the weight is being raised when x = 21 ft. EXERCISES 3.8 1. Area Suppose that the radius r and area A = wr2 of a circle are 6. If x = y3 - y and dy / di = 5, then what is dx/ dt when y = 2? differentiable functions of t. Write an equation that relates dA / dt 7. If x2 + y2 = 25 and dx/ dt = -2, then what is dy/dt when to dr / dt. x = 3 and y = -4? 2. Surface area Suppose that the radius r and surface area 8. If x2y3 = 4/27 and dy/ dt = 1/2, then what is dx/dt when S = 4Tr2 of a sphere are differentiable functions of t. Write an x = 2? equation that relates dS / dt to dr / dt. 9. If L = Vx2 + y2, dx/dt = -1, and dy/dt = 3, find dL/dt 3. Assume that y = 5x and dx/ dt = 2. Find dy / dt. when x = 5 and y = 12. 4. Assume that 2x + 3y = 12 and dy/ dt = -2. Find dx/ dt. 10. If r + s2 + 13 = 12, dr/dt = 4, and ds/ dt = -3, find du/dt 5. If y = x2 and dx/ dt = 3, then what is dy / dt when x = -1? when r = 3 and s = 1