(2)已知a+b =8,ab =16+c 2,求(a ﹣b+c )2018的值.
20.计算:2x 2y (3-x 4y )-(5x 3y )2
21.化简题
(1)22114732ab b ab b -+--
(2)已知:3233329168,3416,A x xy y B x y xy =++=-+求A-2B .
22.(-x )2 • x 3 • (-2y )3 + (-2xy )2 • (-x )3y
23.阅读材料:对于任何数,我们规定一种运算a b
ad bc c d =-. 例如:121423234=⨯-⨯=-.
(1)按照这个规定,请你计算106
34-的值.
(2)请计算当21(2)02x y ++-=时,2223
2x y -的值. 24.(1)
03-321--1+-333()()()÷ (2)20132﹣2012×
2014(简便计算) (3)(3a 2)3+a 2•a 4﹣a 8÷
a 2 (4)(x ﹣2)(3x ﹣1)
(5)(x ﹣1)(x+1)﹣(x+2)2
(6)(a+3b ﹣2c )(a ﹣3b ﹣2c )
(7)(m ﹣2n+1)2
(8)(2a ﹣3b )2(2a+3b )2 .