SOLUTION: The length of a rectangle is 4 centimeters more than its width. If the length is increased by 8 centimeters and the width is decreased by 4 centimeters, the area will remain uncha

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Question 859489: The length of a rectangle is 4 centimeters more than its width. If the length is increased by 8 centimeters and the width is decreased by 4 centimeters, the area will remain unchanged. Find the original dimensions of the rectangle.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x for length, and y for width.

Original Rectangle
x=y%2B4; xy=A which is %28y%2B4%29y=A.
This area simplifies to highlight_green%28y%5E2%2B4y=A%29.

Changed Rectangle
%28x%2B8%29%28y-4%29=A; substituting as for the variables assigned, %28%28y%2B4%29%2B8%29%28y-4%29=A.
This area simplies:
%28y%2B12%29%28y-4%29
highlight_green%28y%5E2%2B8y-48=A%29.

A used in both rectangles because area is specified as equal for both.
This equality means highlight%28y%5E2%2B4y=y%5E2%2B8y-48%29.
Do the rest. This equation becomes linear in y.... See how?