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Difference of squares intro

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Problem

The rectangle below has an area of x, squared, minus, 16 square meters and a width of x, plus, 4 meters.
What expression represents the length of the rectangle?
A rectangle with a width of x plus four and an unknown length. The area of the rectangle is x squared minus sixteen.
start text, L, e, n, g, t, h, end text, equals
meters
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