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Math Help - algebra

  1. #1
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    Post algebra

    The lenght of a rectangle is 3cm greater than its width.the perimeter of the rectangle is 34cm.find its lenght.
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  2. #2
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    Re: algebra

    width=x
    length=x+3
    perimeter=2*(l+b)=34cm(given)
    2(x+x+3)=34
    2x+3=17
    x=7
    length=x+3=7+3=10cm
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  3. #3
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    Re: algebra

    Notice what prasum did. It is a procedure that works for every word problem.

    First, name your variables in writing.

    $width = W.$

    $length = L.$

    $perimeter = P.$

    Second, take all the information that you are given explicitly in the problem or that you are implicitly expected to know and translate it into math speak in writing.

    $P = W + L + W + L = 2W +2L.$

    $P = 34.$

    $L = W + 3.$

    $Find\ value\ of\ L.$

    Third, you now have a pure math problem; all the words are gone. Solve that problem.

    $34 = P\ and\ P = 2W + 2L \implies 2W + 2L = 34.$

    $L = W + 3 \implies 2L = 2(W + 3) = 2W + 6.$

    $So\ 2W + (2W + 6) = 34 \implies 2W + 2W + 6 = 34 \implies 4W = 28 \implies W = 7 \implies L = 10.$

    Fourth, check your answer.

    7 + 3 = 10. Correct.

    2 * 7 + 2 * 10 = 14 + 20 = 34. Correct.

    If you remember to do these four steps for every word problem, you will soon find doing them correctly to be much easier.
    Thanks from Shakarri
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