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化简求值(2x∧2y-4xy∧2)-(-3xy∧2+x∧2y),其中x=-...

(1)原式=-2x-4x+2y+3x-2y+1=-3x+1,当x=-3时,原式=10;(2)原式=xy-2y2-8xy+6y2-2x2y+30y2-4x2y=-7xy+34y2-6x2y,当x=1,y=-2时,原式=162.

原式=4x2y-[6xy-(8xy-4)-x2y]+1,=4x2y-(6xy-8xy+4-x2y)+1,=4x2y-6xy+8xy-4+x2y+1,=5x2y+2xy-3,把x=12,y=2代入上式得:原式=5x2y+2xy?3=?52.

(1)原式=1-x?yx?2y?(x?2y)2(x?y)(x+y)=1-x?2yx+y=x+y?x+2yx+y=3yx+y,当x=2,y=5时,原式=3×52+5=157;(2)原式=(x+2)(x?2)+4(x?2)2?x?2x=x2(x?2)2?x?2x=xx?2,当x=-12时,原式=?12?12?2=15.

原式=(x-2y)^2/(x-2y)-(2x-3y)(2x+3y)/(2x-3y) 分式上下约分=x-2y-(2x+3y) =-x-5y 代入数值=-5

原式=3x2y-6xy+2(4xy-2)+x2y+1=3x2y-6xy+8xy-4+x2y+1=4x2y-2xy-3,当x=-12,y=1时,原式=4×(-12)2×1-2×(-12)×1-3=-1.

解析 (1)4x2y-(6xy-12xy+6-x2y)+1=4x2y-6xy+12xy-6+x2y+1=5x2y+6xy-5,当x=2,y=-12时,原式=5×22×(?12)+6×2×(?12)?5=-10-6-5=-21.(2)原式=3a2b-(2ab2-6ab+3a2b+4ab)-2ab=3a2b-2ab2+6ab-3a2b-4ab-2ab=-2ab2,∵(a+2)2+(3b-3)2=0,∴a...

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