How do you factor $2x^2 + 7x-4$ ?

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Answer 1 · 2016-08-28T15:56:21

$2x^2+7x-4=(2x-1)(x+4)$

Use an AC method:

Find a pair of factors of $AC=2*4=8$ which differ by $B=7$

The pair $8, 1$ works.

Use this pair to split the middle term and factor by grouping:

$2x^2+7x-4$

$=2x^2+8x-x-4$

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

$=2x(x+4)-1(x+4)$

$=(2x-1)(x+4)$

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