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Math Help - Writing Equations - Quadratics 2

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    Writing Equations - Quadratics 2

    The area of a square is triple by adding 10 cm to one dimension and 12 cm to the other. Determine the side length of the square.

    My attempt:

    area = (l)(w)

    3x^2 = 10x + 12x

    This is all I got done, I am pretty sure I am wrong though...
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    Re: Writing Equations - Quadratics 2

    If you let the side of the square be l, then the area of the square is l^2. If you add 10 to one dimension and 12 to the other, then the new area should be given by (l+10)(l+12)=new area (why?). Since you know that the new area is three times the original, you can solve for the length of the square.
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    Re: Writing Equations - Quadratics 2

    Quote Originally Posted by Mathnood768 View Post
    The area of a square is triple by adding 10 cm to one dimension and 12 cm to the other. Determine the side length of the square.

    My attempt:

    area = (l)(w)

    3x^2 = 10x + 12x

    This is all I got done, I am pretty sure I am wrong though...
    Area(initial) = (l)(w)

    3 x Area = (l + 12)(w +10) , go from this now...

    dokrbb
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    Re: Writing Equations - Quadratics 2

    I still do not know what to do after that, I am really bad at math..
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    Re: Writing Equations - Quadratics 2

    Again, you get 3x^2=(x+12)(x+10)

    3x^2=x^2+22x+120

    2x^2-22x-120=0

    x^2-11x-60=0
    (x-15)(x+4)=0

    Two solutions. Choose the one that makes sense. ( one is negative and a square cannot have a negative side)
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  6. #6
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    Re: Writing Equations - Quadratics 2

    Thank you! This makes sense to me now. I am slowly getting better at these word problems.
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