4n^2-36??

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- Apr 17th 2008, 07:10 PMhelpmeefactoring trinomials?
4n^2-36??

- Apr 17th 2008, 07:18 PMJen
Factor out a 4 and use the difference of squares.

Give it a try. It is similar to the earlier ones we did. - Apr 17th 2008, 07:20 PMhelpmee
so n^2-8?

i dont know what to do after that... - Apr 17th 2008, 07:21 PMJen
so your solution should look like $\displaystyle 4(n+c)(n-c)$ Where c is some constant. Remember that you should be able to multiply it all back out and it should look like the original.

- Apr 17th 2008, 07:22 PMo_O
$\displaystyle 4n^{2} - 36 = 4\left(n^{2} - 9\right)$

Since $\displaystyle 36 = 4 \times 9$ - Apr 17th 2008, 07:22 PMJen
- Apr 17th 2008, 07:24 PMhelpmee
mmkay the other one... 27t^2+18t+9 my teacher said its (x-1)(3x+1)...

- Apr 17th 2008, 07:29 PMJen
$\displaystyle 9(t-1)(3t+1)=27t^2-18t-9$ Which is a bit different than the one we started with.

- Apr 17th 2008, 07:31 PMhelpmee
?? so hes wrong??

- Apr 17th 2008, 07:33 PMJen
- Apr 17th 2008, 07:38 PMhelpmee
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.. - Apr 17th 2008, 08:55 PMo_O
How did the negative sign appear randomly?

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

which can't be factored.