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Math Help - Rectangle problem

  1. #1
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    Rectangle problem

    Hello it's Liz again. I have another problem but I half way know what do. Here is the problem: If the sides of a square are lengthened by 8cm, the area becomes 225 cm^2. Find the length of a side of the original square.

    This is what I have so far: x+8cm
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  2. #2
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    Quote Originally Posted by lizann View Post
    Hello it's Liz again. I have another problem but I half way know what do. Here is the problem: If the sides of a square are lengthened by 8cm, the area becomes 225 cm^2. Find the length of a side of the original square.

    This is what I have so far: x+8cm
    Here is a diagram

    Rectangle problem-capture.jpg

    so to find the area of the big square we multiply the base times the height, but we know the area is 225 square cm so


    (x+8)(x+8)=225

    (x+8)^2=225 \iff \sqrt{(x+8^2)}=\sqrt{225}

    x+8=\pm 15 \iff x=-8 \pm 15

    Since length can't be negative we will only use the postive root

    x=-8+15=7

    So the length of the orginal square is 7 cm.

    Yeah!!!
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  3. #3
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    Thanks very much

    Thank you very much you are extremely smart and well in math. I could really use a lot of help if you are willing to help. I'm placed in a math class that I don't really understand at all. I have done majority of the question i just have about five left. Can you help me with the rest of the math problems? If not thanks anyway you were a huge help. Problem better than my instructor.
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