Question 54870: I could really use some help with this problem. Thanks! The area of a rectangle is 45 square cm. If the length is 4 cm greater than the width, what are the dimension of the rectangle?
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! The area of a rectangle is 45 square cm. If the length is 4 cm greater than the width, what are the dimension of the rectangle?
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Write an equation which translates the following sentence:
"the length is 4 cm greater than the width," (the word "is" usually means "=")
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L = W + 4
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We know that:
L * W = 45 sq cm
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Substitute (W + 4) for L, and you have:
(W+4) * W = 45
:
W^2 + 4W = 45
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W^2 + 4W - 45 = 0; our old friend the quadratic equation
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Factors easily to:
(W + 9) (W - 5) = 0
:
W = -9
and
W = +5, the positive solution is what we want in the real world
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L = 5 + 4 = 9: Checks out: 9 * 5 = 45
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