How do you factor #9x^3+36x^2-4x-16#?

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Answer 1 · 2017-01-08T16:35:49

The answer is #=color(red)((x+4))color(blue)((3x+2)(3x-2))#

We use

#a^2-b^2=(a+b)(a-b)#

#9x^2-4=(3x+2)(3x-2)#

Therefore, we start factorising

#9x^3+36x^2-4x-16#

#=9x^2color(red)((x+4))-4color(red)((x+4))#

#=color(red)((x+4))color(blue)((9x^2-4))#

#=color(red)((x+4))color(blue)((3x+2)(3x-2))#