(1) 7-3x-4x 2+4x-8x 2-15
(2) 2(2a 2-9b)-3(-4a 2+b)
(3) 8x 2-[-3x-(2x 2-7x-5)+3]+4x
(4) -32009)2
14(2)2(++--y x y x (5) -[]12)1(32--+--n m m
(9)1}1]1)1([{2222-------x x x x
(10)(2x-3y)+(5x+4y)
(11)(8a-7b)-(4a-5b)
(12)a-(2a+b)+2(a-2b)
(13)3(5x+4)-(3x-5)
(14)x+[x+(-2x-4y)]
(15)(a+4b)- (3a-6b)
(16)3x 2-1-2x-5+3x-x 2
(17) (a+4b)- (3a-6b)
(18)4x+2y —5x —y
(19)—3ab+7—2a 2—9ab —3
(20)7x 2-2x+3x-7x 2
(21)-0.8a 2b-6ab-1.2a 2b+5ab+a 2b
(23)6x 2y+2xy-3x 2y 2-7x-5yx-4y 2x 2-6x 2y
(24)8x +2y +2(5x -2y )
(25)3a -(4b -2a +1)
(26)7m +3(m +2n )
(27)(x 2-y 2)-4(2x 2-3y 2)
(28)-4x +3(3
1x -2) (29)5(2x-7y)-3 (4x-3y)
(37))]12(45[3---x x x
(38)(3x-5y)-(6x+7y)+(9x-2y)
(39)-1-7x+3x-7x 2
(41)-3(2x 3y -3x 2y 2+3xy 3)
(43)4x 2y-8xy 2+7-4x 2y+12xy 2-4
(44)a 2-2ab+b 2+2a 2+2ab - b 2
(45)先化简,再求值:)4(3)12
5(23m m m -+--,其中3-=m . (46)化简:)32()54(72
2222ab b a ab b a b a --+-+. (47))]21(3)13(2[22222x x x x x x ------- 其中:2
1=x (48))22()(3)2(2222222b a ab b a ab b a ab -+--- 其中:1,2==b a
(49)已知:A=2244y xy x +- ,B=225y xy x -+,求(3A-2B )-(2A+B )的值。
(50)若()0322
=++-b a ,求3a 2b -[2ab 2-2(ab -1.5a 2b )+ab]+3ab 2的值; 参考答案:
(1) 7-3x-4x 2+4x-8x 2-15 == -12x 2+x-8
(2) 2(2a 2-9b)-3(-4a 2+b) == 16a 2-21b
(3) 8x 2-[-3x-(2x 2-7x-5)+3]+4x==10x 2-8
(4))3
12(65++-a a =3-14a (5)b a b a +--)5(2= 3a -4b
(6)(6)-32009)2
14(2)2(++--y x y x = -14x +2y +2009 (7)-[]12)1(32--+--n m m = m -3n +4
(8))(4)()(3222222y z z y y x ---+- = 2y 2+3x 2-5z 2
(9)1}1]1)1([{2222-------x x x x =0
(10)(2x-3y)+(5x+4y)=7x+y
(11)(8a-7b)-(4a-5b)=4a-2b
(12)a-(2a+b)+2(a-2b)=a-5b
(13)3(5x+4)-(3x-5)=12x-17
(14)x+[x+(-2x-4y)]=-4y