a. 7x - 7y
= 7(x-y)
b. x2 - 6xy + 9y2
= (x - 3y)2
a) 7(x-y)
b) (x-3y)2
c) xy(x+y)-(x+y)=(xy-1)(x+y)
d) x2-3x+2x-6=x(x-3)+2(x-3)=(x+2)(x-3)
c. x2y +xy2 -x -y
=( x2y -x ) + (xy2 - y)
= x( xy -1 ) + y (xy -1)
= (xy -1) (x+y)
d. x2 - x - 6
= x2 - 3x + 2x -6
= x( x -3) + 2 (x-3)
=(x-3) ( x+2)