How do you factor #3x^2 + 28x + 32#?

1 Answer
EZ as pi
Sep 27, 2016

#(3x+4)(x+8)#

Explanation:

#3x^2 +28x +32#

Find factors of 32 which ADD to make 28.
The signs are the same both positive

As 3 isa prime number, its only factors are 3 and 1.

As a start, ask what factors of 32 can we use to get to just less than 28. (we still have to ADD on something...)

#3xx8 = 24# seems a possible start.
Choose factors and cross-mulitply

#color(white)(xxx)3color(white)(xxx)32#

#color(white)(xxx)3color(white)(xxxx)4 " "rarr 1xx4 =4#
#color(white)(xxx)1color(white)(xxxx)8" "rarr3xx8 = ul24#
#color(white)(xxxxxxxxxxxxxxxxxxxx)28#

#(3x+4)(x+8)#

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