A cube has side length x One side of the cube is increased by 4 inches, and another side is doubled. The volume of the new rectangular prism is 450 cubic inches. The equation 2 x cubed plus 8 x squared is equal to 450 can be used to find x What was the side length of the original cube? Use a graphing calculator and a system of equations to find the answer.
Graph y = 2x³ + 8x² and y = 450; their positive intersection occurs at x = 5. Checking: 2(5³) + 8(5²) = 250 + 200 = 450. Therefore, the original cube’s side length was 5 inches, choice B.
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