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Surface Area 17. Find the area of the surface generated when y = 8"; on [9, 20] is revolved about the x-axis. 18. Find the area of the surface generated when y = V 5x x2 on [1, 4] is revolved about the x-axis. 19. Find the area of the surface generated when y =(3x)"3 on 8 0 S x g E is revolved about the y-axis. x3 20. Find the area of the surface generated when y = ? + 4 on [112, 2] x is revolved about the x-axis