Algebra

Algebra Level 1

Factor:

− 2 x 3 − 6 x 2 + 56 x . -2x^3-6x^2+56x .

− 2 x ( x − 4 ) ( x + 7 ) -2x(x-4)(x+7) ( x − 4 ) ( x + 7 ) (x-4)(x+7) ( 3 x + 2 ) 2 (3x+2)^2 2 ( x − 4 ) ( x + 7 ) 2(x-4)(x+7)

Bob Joe by Bob Joe , 22, USA

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2 solutions

Ashish Menon
Jun 29, 2016

− 2 x 3 − 6 x 2 + 56 x = − 2 x 3 + 8 x 2 − 14 x 2 + 56 x = − 2 x 2 ( x − 4 ) − 14 x ( x − 4 ) = ( − 2 x 2 − 14 x ) ( x − 4 ) = − 2 x ( x − 4 ) ( x + 7 ) \begin{aligned} -2x^3 - 6x^2 + 56x & = -2x^3 + 8x^2 - 14x^2 + 56x\\ & = -2x^2\left(x-4\right) - 14x\left(x-4\right)\\ & = \left(-2x^2 - 14x\right)\left(x - 4\right)\\ & = \color{#3D99F6}{\boxed{-2x\left(x-4\right)\left(x + 7\right)}} \end{aligned}

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Pham Khanh
Apr 25, 2016

− 2 x 3 − 6 x 2 + 56 x -2x^{3}-6x^{2}+56x = [ − 2 x ( x 2 ) ] + [ − 2 x ( 3 x ) ] + [ − 2 x ( − 28 ) ] =[-2x(x^{2})]+[-2x(3x)]+[-2x(-28)] = − 2 x ( x 2 + 3 x − 28 ) =-2x(x^{2}+3x-28) = − 2 x ( x 2 + 7 x − 4 x − 28 ) =-2x(x^{2}+7x-4x-28) = − 2 x [ x ( x + 7 ) − 4 ( x + 7 ) ] =-2x[x(x+7)-4(x+7)] = − 2 x ( x − 4 ) ( x + 7 ) =\large \boxed{-2x(x-4)(x+7)}

1 Helpful 0 Interesting 0 Brilliant 0 Confused

Moderator note:

Simple standard approach.

You are missing a bracket on the second last line.

Jesse Nieminen - 4 years, 11 months ago

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Thanks. Edited

Pham Khanh - 4 years, 11 months ago

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