求下列各式的值2y-xy分之x的平方-2x,其中x=-6,y=28
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(xy+2)(xy-2)-2x^2y^2+4=x^2y^2-4-2x^2y^2+4=-x^2y^2=-10^2*(-1/25)^2=-(10/25)^2=-(2/5)^2=-4/25
1,x(x-y)=8y(x-y)=3(x+y)(x-y)=13x的平方-y的平方=(x+y)(x-y)=132,x的平方-xy=8xy-y的平方=3x的平方-2xy+y的平方=8-3=5
因为x有绝对值和y有平方,所以〡X-2〡=0,﹙3-Y﹚²=0x=2,y=3将x=2,y=3代入原式=2³=8原式=2/(2*3)-(2*3)=1/3-6=-17/3再问:��ô再
x+2的绝对值+(3-y)的平方=0所以x+2=0,x=-23-y=0,y=3(1)x²=2²=4(2)题目不完整..再问:x的y次方-xy分之x再答:x的y次方-xy分之x=(-
1.x²y+xy²=xy(x+y)=3×2=62.(x-y)²=(x+y)²-4xy=4-12=-8
(x-y)²=x²+y²-2xy=x²+y²+2xy-4xy=(x+y)²-4xy=3²-4•(-1/4)=9+1=1
x^2+2xy+y^2=x²+xy+xy+y²=(x²+xy)+(xy+y²)=8+3=11x²-y²=x²+xy-xy-y
因为X:2=3:4所以4X=6X=1.5(2)因为X-1分之X+2=2所以2(X-1)=X+22X-2=X+2X=4这样回答要得不嘛
(1)x2-2xy+4y2=(x-2y)2+2xy=11,将x-2y=3代入得:xy=1;(2)∵xy=1,x-2y=3,∴x2y-2xy2=xy(x-2y)=1×3=3.
(1)x^2+y^2=x^2+y^2+2xy-2xy=(x+y)^2-2xy=8^2-2*15=64-30=34(2)(x-y)^2=x^2+y^2-2xy=(x^2+y^2+2xy)-4xy=(x+
x-1/2x²-2=(x-1)/2(x²-1)=(x-1)/2(x+1)(x-1)=1/2(x+1)=1/2(-2+1)=-1/2x²-4xy+4y²/2x-4
(1)∵x+y=4,xy=3,∴(x-y)2=x2-2xy+y2=(x+y)2-4xy=16-12=4;(2)∵x+y=4,xy=3,∴x2y+xy2=xy(x+y)=12.
(1)∵x+y=7,∴x2+2xy+y2=49,∵xy=2,∴x2+2×2+y2=49,解得x2+y2=45,∴2x2+2y2的值是90;(2)∵x2+y2=45,xy=2,∴(x-y)2=x2-2x
(每小题(3分),共6分)(1)原式=2xy(x+2y)∵x+2y=5,xy=1,∴2xy(x+2y)=2×1×5,=10;(2)∵xy=1,x+2y=5,原式=2x2y2-x2-4y2+2∴=-4x
这道题考察的是技巧算题并非硬算(当然算出即可).因为x+y=-1,所以(x+y)^2=1.再将(x+y)^2打开得x^2+y^2+2xy=1.又因为xy=-12.所以x^2+y^2=1-2xy=25.
解x/y=3∴x=3y∴(x²+xy)/y²=(9y²+3y²)/y²=12y²/y²=12最简公分母(x-1)²(x+
,①X^2+Y^2=(x+y)²-2xy=3²-2×(-12)=33②X^2-XY+Y^2=33-(-12)=45
1)x²+y²=(x²-xy)+(xy+y²)=4+(-3)=12)x²+2xy+3y²=(x²-xy)+3(xy+y²
(1)x²-y²=(x²+xy)-(xy+y²)=3-(-2)=5(2)x²+4xy+3y²=(x²+xy)+3(xy+y
∵x²-xy=8,xy-y²=3∴x²-xy+xy-y²=3+8∴X²-Y²=11∴x²-xy﹣﹙xy-y²﹚=8-3∴