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anonymous

  • 5 years ago

I need help on quadratic equations its so difficult the problem is (x+4) (x-9)=4x can someone please help me

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  1. anonymous
    • 5 years ago
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    You need to expand the left-hand side and collect like terms. You will end up with another quadratic which you can factor and solve.

  2. anonymous
    • 5 years ago
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    \[(x+4)(x-9)=4x \iff x^2+4x-9x-36=4x \iff x^2-9x-36=0\]which may be factored\[(x+3)(x-12)=0\]

  3. anonymous
    • 5 years ago
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    x^2-9 x-36 = 0

  4. anonymous
    • 5 years ago
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    Your solutions are then \[x=-3, x=12\]

  5. anonymous
    • 5 years ago
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    (x-12)(x+3)

  6. anonymous
    • 5 years ago
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    Foil the (x+4)(x-9) which comes out as x^2-5x-36=4x then you subtract 4x on both sides which leaves you with x^2-9x-36=0 then factor it to (x-12)(x+3)=0 x=12 x=-3

  7. anonymous
    • 5 years ago
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    Thank you all very much

  8. anonymous
    • 5 years ago
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    welcome

  9. anonymous
    • 5 years ago
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    Can someone explain to me how to do quadratic equations, im confused?

  10. anonymous
    • 5 years ago
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    Look under 'algebra' on this site. In the second column, there should be stuff for the quadratic equation. http://www.khanacademy.org/

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