How do you factor $x^2 + 2x + 4x + 8$ by grouping?

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Answer 1 · 2016-05-15T10:41:53

$x^2+2x+4x+8=(x+4)(x+2)$

Group the terms using parentheses:

$(x^2+2x)+(4x+8)$

Identify the common factor inside each pair of parentheses and separate it out:

$x(x+2)+4(x+2)$

Combine the coefficients of the common factor:

$(x+4)(x+2)$

I would normally simply write this:

$x^2+2x+4x+8$

$=(x^2+2x)+(4x+8)$

$=x(x+2)+4(x+2)$

$=(x+4)(x+2)$

How do you factor x^2 + 2x + 4x + 8x^2 + 2x + 4x + 8 by grouping?