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Math Help - Solve Length of a Rectangle

  1. #1
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    Solve Length of a Rectangle

    The length of a rectangle is 5 feet more than the width. The area of the rectangle is 24 square feet. How long is the rectangle?

    Now I know it is 8feet long and 3 feet wide...but when I do the following I come out with the wrong answer. Where are am going wrong.

    area= length * width
    24= length * (width +5)

    ...at a lost really. please help
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  2. #2
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    Quote Originally Posted by thecapaccino View Post
    The length of a rectangle is 5 feet more than the width. The area of the rectangle is 24 square feet. How long is the rectangle?

    Now I know it is 8feet long and 3 feet wide...but when I do the following I come out with the wrong answer. Where are am going wrong.

    area= length * width
    24= length * (width +5)

    ...at a lost really. please help
    Call the width of the rectangle w. The the length, l = w + 5.
    A = l*w

    24 = (w + 5)w

    24 = w^2 + 5w

    w^2 + 5w - 24 = 0

    (w - 3)(w + 8) = 0

    Thus w = 3 or w = -8. But we can't have a negative width, so the width must be w = 3 ft.

    Thus l = 3 ft + 5 ft = 8 ft.

    -Dan
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