0.3x 2y分之0.5x-0.2y
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x2y+xy2-x-y=xy(x+y)-(x+y)=(x+y)(xy-1)∵x+y=-5,xy=7,∴原式=-5×(7-1)=-30.
(3x2y-2xy2)-(xy2-2x2y)=3x2y-2xy2-xy2+2x2y=5x2y-3xy2当x=-1,y=2时,原式=5×(-1)2×2-3×(-1)×22=10+12=22.
5x2y+(-6x2y)+34x2y=14x2y答:和是-14x2y.
[2x(x2y-xy2)+xy(xy-x2)]÷x2y=[2x3y-2x2y2+x2y2-x3y]÷x2y=x-y,把x=2013,y=2012代入上式得:原式=x-y=2013-2012=1.
原式=2x2y+2xy-3x2y-3xy-4x2y=-5x2y-xy当x=-2,y=12时,原式=-9.
3x2(a+3)-4x2y(a+3)=x2(a+3)(3-4y),当a=-0.5,x=3,y=1时,原式=32×(-0.5+3)×(3-4×1)=-22.5.
x2y−x−y2y−x=x2−y2y−x=(x−y)(x+y)y−x=−(x+y)=−x−y.故选A.
解:0.3分之x-1-0.5分之x+2=125x-1.5-3x+3=182x=16.5x=8.25
0.5分之x=0.3分之x-180.3X=0.5(x-18)0.2X=9X=45再问:过程再详细一点,谁除谁都写下来,要不不明白
x/0.5=x/0.3-18两边同乘以0.15(即0.5×0.3=0.15):0.3x=0.5x-2.70.5x-0.3x=2.70.2x=2.7x=2.7/0.2=13.5;
原式=(4x2y+5xy2+3x-2y+5)-2(2x2y-3xy2-2x+1)=4x2y+5xy2+3x-2y+5-4x2y+6xy2+4x-2=11xy2+7x-2y+3.
把X=3;Y=-2代入即可解
原式=4x2y-6xy+3(4xy-2)+x2y+1=5x2y+6xy-5当x=2,y=-12时,原式=5×4×(-12)+6×2×(-12)-5=-21.
化简得:9-12Y^2+6Y+4+12Y^2+4Y-10-10Y+X-Y+1=X-Y+4带入X、Y值得:=3
x=2013,y=2013[3x(x²y-xy²)+xy×(3xy-2x²)]/(x²y)=[3x²y(x-y)+x²y×(3y-2x)]/
(X+Y)2=1402X2Y*3=14400(X+Y)2=140→X+Y=70→Y=70-X①2X2Y*3=14400→XY=1200②把①代人②得:X(70-X)=1200X²-70X+1
0.3分之1-0.5x减0.3分之0.2x-1=0.02分之0.3x两边乘0.31-0.5x-0.2x+1=4.5x4.5x+0.5x+0.2x=25.2x=2x=5/13如果本题有什么不明白可以追问
题目1看不明白解题目2x+y=4,(x+y)^2=4^2=16,同样x-y=10,(x-y)^2=10^2=100,(x+y)^2=x^2+2xy+y^2,(x-y)^2=x^2-2xy+y^2,(x
代入x=-1,y=1,2x^y-(5xy^-3x^y)-x^=2*(-1)^*1-{5*(-1)*1^-3*(-1)^*1}-(-1)^=2-(-5-3)-1=9备注:2^表示2的平方
原式=2x2y+2xy-3x2y+3xy-4x2y=-5x2y+5xy,当x=-1,y=1时,原式=-5×(-1)2×1+5×(-1)×1=-5-5=-10.