How do you factor completely $12x^2-27$ ?

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Answer 1 · 2016-05-13T17:12:12

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

In factoring - always look for a common factor first.

After taking out a common factor, the number of terms in the expressions is a huge clue as to what type of factorising it might be:

4 or more terms $rArr "grouping"$
3 terms $rArr " quadratic trinomial"$
2 terms $rArr "difference of two terms"$

$12x^2 - 27 = 3(4x^2 - 9)$

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

How do you factor completely 12x^2-2712x^2-27?