what are the factors of 3x2– 33x + 84

Question

jack1 · Answer

3(x-7)(x-4)

jack1 · Answer

would you like to know how to do it?

ladiesman217 · Answer

yes plz

jack1 · Answer

Have you heard of FOIL before?
First terms,
Outer terms,
Inner terms,
Last terms

ladiesman217 · Answer

ya

jack1 · Answer

cool, then you know that's how you times out the factors to get the equation, so essentially we're doing the opposite:
so first you look at the equation as:

jack1 · Answer

$$ax ^{2}+ bx +c$$

jack1 · Answer

in our case:
a = 3
b = -33
c= 84
so... what are the factors of our "a" term? (3)

jack1 · Answer

basically: what times what = 3?

ladiesman217 · Answer

1*3

jack1 · Answer

perfect, so our factors for a will be 3 and 1
so it's starting to look like:
(3x + __ ) (1x + __ )

jack1 · Answer

next, "c" = Last term times Last term
in our case c = 84
so what times what = 84?

jack1 · Answer

1,84  2,42  3,28  4,21, 6,14  7,12

jack1 · Answer

we cant pick it yet, so we work our the b term's factors
these factors will add to equal -33 and multiply to equal 84
remember from foil though that it's Outer terms + Inner terms will equal b
(so don't forget the 3x)

anonymous · Answer

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