1 ( 1) 7-3x-4x2+4x-8x2-15 (2) 2(2a2-9b)-3(- 4a2+b) (3) 8x2-[-3x-(2x2-7x-5)+3]+4x (4) )312(65aa (5) baba)5(2 (6) - 32009)214(2)2(yxyx (7) - 12)1(32nmm (8) )(4)()(3222222yzzyyx (9)1}1]1)1([{2222xxxx 2 ( 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)3x2-1-2x-5+3x-x2 (17) (a+4b)- (3a-6b) (18)4x+2y— 5x— y ( 19)—3ab+7— 2a2— 9ab— 3 3 ( 20) 7x2-2x+3x-7x2 ( 21) -0.8a2b-6ab-1.2a2b+5ab+a2b ( 22)222baba43ab21a32 ( 23) 6x2y+2xy-3x2y2-7x-5yx-4y2x2-6x 2y ( 24) 8x+ 2y+ 2( 5x- 2y) ( 25) 3a-(4b- 2a+ 1) ( 26) 7m+ 3( m+ 2n) ( 27)(x2- y2)-4( 2x2- 3y2) ( 28)-4x+ 3( 31 x- 2) ( 29) 5(2x-7y)-3 (4x-3y) 4 ( 30)baba22212 ( 31)bababa2222132 ( 32)322223babbaabbaa ( 33)5253432222xyyxxyyx ( 34)bababa2222132 ( 35)322223babbaabbaa ( 36)13243222xxxxxx ( 37))]12(45[3xxx ( 38) (3x-5y)-(6x+7y)+(9x-2y) (39)-1-7x+3x-7x2 (40))3(2)2(322bababa 5 (41)- 3(2x3y- 3x2y2+ 3xy3) (42)222234(3)xxxxx ( 43) 4x2y-8xy2+7-4x2y+12xy2-4 (44)a2-2ab+b2+2a2+2ab - b2 ( 45)先化简,再求值:)4(3)125(23mmm,其中3m. (46)化简:)32()54(722222abbaabbaba. ( 47))]21(3)13(2[22222xxxxxx 其中:21x ( 48))22()(3)2(2222222baabbaabbaab 其中:1,2ba ( 49)已知:A=2244yxyx , B=225yxyx,求(3A-2B)-(2A+B)的值。 ( 50)若0322 ba,求3a2b- [2ab2- 2( ab- 1.5a2b) +ab]+3ab2的值; 6 参考答案: ( 1) 7-3x-4x2+4x-8x2-15 == -12x2+x-8 (2) 2(2a2-9b)-3(- 4a2+b) == 16a2-21b ( 3) 8x2-[-3x-(2x2-7x-5)+3]+4x==10x2-8 (4))312(65aa=3- 14a (5)baba)5(2= 3a-4...