先化简在求值x减2y x加3y减2x减y
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依相反数的意义有|x-y+3|=-|x+y-1999|.因为任何一个实数的绝对值是非负数,所以必有|x-y+3|=0且|x+y-1999|=0.即x−y+3=0①x+y−1999=0②,由①有x-y=
y=√(x-2)+√(2-x)+3有意义则需x-2≥0且2-x≥0只有x-2=0,∴x=2∴y=0+0+3=3y^x=3²=9y^x的平方根为±√9=±3
1、=3(x+2)-x=3x+6-x=2x+6把x=-3/2代入得=-3+6=32、2x+y=5x-3y=5(2)*22x-6y=10(3)(1)-(3)7y=-5y=-5/7代入(2)得:x=5+1
已知绝对值x加1加y加2括号的平方等于0x+1=0,y+2=0x=-1,y=-23减2xy加3yx的平方加6xy减4x的平方y=3+4xy-x平方y=3+4×1×2-1×(-2)=11+2=13
c再问:真的是c吗?再答:百分百正确再问:那好谢谢你了。
2x+yx2-2xy+y2•(x-y)=2x+y(x-y)2•(x-y)(2分)=2x+yx-y;(4分)当x-3y=0时,x=3y;(6分)原式=6y+y3y-y=7y2y=72.(8分)
将x=1,y=2带入方程x-2y+3k=0得:1-2*2+3k=03k=3k=1所以k的值为1
(x2-y2)/(x-y)2=(x+y)/(x-y)代入x、y得√3/6
(x²+x-2)分之(1+x)÷[x-2+(x+2)分之3]=(x²+x-2)分之(1+x)÷[(x+2)分之(x²-1)]=[(x+2)(x-1)]分之(1+x)×(x
2(x^2y+2y^2-xy^2)-(2yx^2-3xy^2+3x^2)=2x²y+4y²-2xy²-2x²y+3xy²-3x²=4y
2(x^2y+2y^2-xy^2)-(2yx^2-2xy^2+3x^3)=2x^2y+4y^2-2xy^2-2x^y+2xy^2-3x^3=4y^2-3x^3=4*2^2-3*(-3)^3=16+81
x=2y=1
3-2xy+3yx²+6xy-4x²y=3+4xy-x²y=3+1x2+(-1)²x2=3+2+2=7
原式=2XY+3YX^2+6XY-6X^2Y吧=8XY-3X^2Y=XY(8-3X)代入已知数:原式=-2*(8-3/2)=-13
|x+3|+(y-1/2)^2=0|x+3|=0,(y-1/2)^2=0x=-3y=1/26x^2y+2xy-3x^2y^2-7x-5yx-4y^2x^2-6x^2y=6x^2y-6x^2y+2xy-
[23x-2x+y(x+y3x-x-y)]÷x−yx=(23x-23x+2)×xx−y=2xx−y,∵5x+3y=0,∴y=-53x,∴原式=2xx+53x=34.
2(x+x²y)-3分之2(6x²y+3x)-y=2x+2x²y-4x²y-2x-y=-2x²y-y=-2×1²×3-3=-9
原式=x²-2xy+y²+6x²+3xy-4xy-6x²+xy=x²-2xy+y²=(x+y)²当x=2分之1,y=1时,原式=(