SOLUTION: please factor out this problem. x^2-12x-45 thank you

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Question 194110: please factor out this problem.

x^2-12x-45

thank you
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
x^2-12x-45
Rewrite:
x^2-15x+3x-45
x(x-15)+3(x-15)
(x-15)(x+3)
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Cheers,
Stan H.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Set it equal to 0 to find the factors
x%5E2+-+12x+-+45+=+0
Completing the square:
Take 1/2 of rhe coefficient of the x term, square it,
then add it to both sides:
First add 45 to both sides
x%5E2+-+12x+=+45
x%5E2+-+12x+%2B+%2812%2F2%29%5E2+=+45+%2B+%2812%2F2%29%5E2
x%5E2+-+12x+%2B+144%2F4+=+45+%2B+144%2F4
x%5E2+-+12x+%2B+36+=+45+%2B+36
Like magic, the left side becomes a perfect square:
%28x+-+6%29%5E2+=+81
Now take the square root of both sides
x+-+6+=+9
and
x+-+6+=+-9
from these, I get:
x+=+15
x+=+-3
And now I write them as the factors of 0
x+-+15+=+0
x+%2B+3+=+0
So,
%28x+-+15%29%28x+%2B+3%29+=+0
Cool, or what?