1, a ( a - b ) ( a + b ) - ( a + b ) ( a2 - ab + b2 )
= ( a + b ) [ a ( a - b ) - ( a2 - ab + b2 )
= ( a + b ) ( a2 - ab - a2 + ab - b2 )
= ( a + b ) b2
.......
2, 3x ( x + 7 )2 - 11x2 ( x + 7 ) + 9 ( x + 7 )
= ( x + 7 ) [( 3x ( x + 7 ) - 11x2 + 9 ]
= ( x + 7 ) ( 3x3 + 21x - 11x2 + 9)
= ( x + 7 ) ( - 8x2 + 21x + 9 )
..........
3, 4x ( x - 2y ) + 8y ( 2y - x )
= 4x ( x - 2y ) - 8y ( x - 2y )
= ( 4x - 8y ) ( x - 2y )
= 4 ( x - 2y ) ( x - 2y )
= 4 ( x - 2y )2
1,a(a-b)(a+b)-(a+b)(a2-ab+b2)=(a+b)[a(a-b)-a2+ab-b2]
=(a+b)(a2-ab-a2+ab-b2)
=(a+b)(-b2)=-b2(a+b)