Question

12. (1) ( 1-2 a b-left(a^{2}+b^{2}right) ) ( =1-left[2 a b+a^{2}+b^{2}right] )
( =(1)^{2}-(a+b)^{2} )
( =(1+a+b)(1-a-b) )
( left[because a^{2}-b^{2}=(a+b)(a-b)right] )

# 12. 1- 2ab - (a + b) का एक गुणनखण्ड है। (1) (1+ a + b) (2) (1 - a + b) (3) (1 + a-b) (4) (-1-a- b)

Solution