Question 57396: factoring trinomials by trial and error
x^2-8x+12
Answer by funmath(2933) (Show Source):
You can put this solution on YOUR website! factoring trinomials by trial and error
x^2-8x+12
The factors that make x^2 are:
x*x
That is the first term of each parenthesis:
12 is p0sitive so the factors have the same sign, because they add to get -8 they both are negative:
-1*-12, -2*-6,-3*-4
You try the possible answers until you find the one that works:
(x-1)(x-12)=x^2-12x-x+12=x^2-13x+12 ERROR
(x-2)(x-6)=x^2-6x-2x+12=x^2-8x+12 Correct, this is the one!!!
:
To facilitate the process, when there is no number in front of x^2, ask yourself, what two numbers multiply to give me +12, but add to give me -8? It's easier to come up with the right factors that way:
-2*-6=12 and -2+-6=-8
x^2-8x+12=(x-2)(x-6)
You don't have to deal with ther ERRORs this way.
Happy Calculating!!!
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