How do you factor by grouping: $1-a+ab-b$ ?

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Answer 1 · 2018-03-04T08:19:12

Group 'em together
$ab-a+1-b$

$ab-a=a(b-1)$
Notice that there will be a 1 as without it it'll simply be $ab$

$1-b=1(1-b)$
Notice that it doesn't match with the upper one... so we'll change the signs
$1(1-b)=-1(b-1)$ (try to multiply them now!!

Jot them down in one expression
$a(b-1)-1(b-1)$
You get!!!!!!
$(a-1)(b-1)$

How do you factor by grouping: 1-a+ab-b1-a+ab-b?