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Math Help - factoring trinomials?

  1. #1
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    factoring trinomials?

    4n^2-36??
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  2. #2
    Jen
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    Factor out a 4 and use the difference of squares.

    Give it a try. It is similar to the earlier ones we did.
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  3. #3
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    so n^2-8?
    i dont know what to do after that...
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  4. #4
    Jen
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    so your solution should look like 4(n+c)(n-c) Where c is some constant. Remember that you should be able to multiply it all back out and it should look like the original.
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  5. #5
    o_O
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    4n^{2} - 36 = 4\left(n^{2} - 9\right)

    Since 36 = 4 \times 9
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  6. #6
    Jen
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    Quote Originally Posted by helpmee View Post
    so n^2-8?
    i dont know what to do after that...

    I believe that you should end up with 4(n^2-9)

    But don't forget how you factored the n^2-16

    You remember that one?

    Do the same with n^2-9
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  7. #7
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    mmkay the other one... 27t^2+18t+9 my teacher said its (x-1)(3x+1)...
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  8. #8
    Jen
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    9(t-1)(3t+1)=27t^2-18t-9 Which is a bit different than the one we started with.
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  9. #9
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    ?? so hes wrong??
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  10. #10
    Jen
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    Quote Originally Posted by helpmee View Post
    ??
    You said the original problem was 27t^2+18t+9

    Your instructor's factoring would give us 27t^2-18t-9

    Were they supposed to be negative? Did you write the problem down wrong?
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  11. #11
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    hmm so whats the correct factoring? becuase heres his reasoning...

    27t^2+18t+9

    so

    3t^2-2t+1

    and then you do

    (1x-1) (3x+1)

    and thats because FOIL

    so -1x(3x)=-3x
    and -1(1)=2x
    so the answer when you put them together is -2 which is in the 3t^2+18t+9...

    i dont get that...does it make sense?


    and no i DID copy it right thats why im so confused too..
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  12. #12
    o_O
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    How did the negative sign appear randomly?

    27t^{2}{\color{red}+}18t + 9 = 9\left(3t^{2} {\color{red}+} 2t + 1\right)

    which can't be factored.
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