How do you factor $6ab − 8a + 21b − 28$ ?

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Answer 1 · 2016-07-18T06:36:16

$6ab-8a+21b-28=(2a+7)(3b-4)$

Notice that the ratio between the first and second terms is the same as that between the third and fourth terms.

So this will factor by grouping:

$6ab-8a+21b-28$

$=(6ab-8a)+(21b-28)$

$=2a(3b-4)+7(3b-4)$

$=(2a+7)(3b-4)$

How do you factor 6ab − 8a + 21b − 286ab − 8a + 21b − 28?