How do you factor completely $6x^2 + x - 15$ ?

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Answer 1 · 2016-03-11T22:06:44

$6x^2+x-15=(3x+5)(2x-3)$

Use an AC method: Look for two factors of $AC = 6*15 = 90$ which differ by $B=1$ .

The pair $9, 10$ works.

Then use that pair to split the middle term and factor by grouping:

$6x^2+x-15$

$=6x^2-9x+10x-15$

$=(6x^2-9x)+(10x-15)$

$=3x(2x-3)+5(2x-3)$

$=(3x+5)(2x-3)$

How do you factor completely 6x^2 + x - 156x^2 + x - 15?