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G asked in Science & MathematicsMathematics · 1 decade ago

can somebody explain this to me?

I got this as an answer on a previous post, and one thing doesn't make sense---where did the 24y come from?

2y^2 +13y -132 = 0

2y^2 + 24y - 11y - 132 = 0 2y(y + 12) -11(y + 12) = 0

(2y - 11) (y + 12) = 0

2y - 11 = 0

2y = 11

y = 11/2

y = 5 1/2

y + 12 = 0

y = -12

1 Answer

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  • Anonymous
    1 decade ago
    Favorite Answer

    its something called factor by grouping

    typical equation

    ax^2+bx+c=0

    first you multiply the "a" and the "c" together

    next you have to find two that when multiplied together equal the number acquired in the first step "a*c", but you also have to make sure that when those numbers are added together they equal "b"

    So really they got the 24y and the -11y by trial and error.

    And if you notice 24y -11y= 13y which is equal to their original "b". Also 24*-11= 2*-132

    Source(s): Math tutor
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