x² y²=1,x y分之xy的最小值
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因为x-y=4xy所以x-2xy-y=2xy2x+3xy-2y=11xyx-2xy-y分之2x+3xy-2y=5.5
=(xy-x的平方)除以(x的平方-2xy+y的平方\xy)乘以(x-y\x的平方)=-x(x-y)×xy/(x-y)2×(x-y)/x2=-y再问:嗯
3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2
1/x+1/y=-2则(x-xy+y)/(x+xy+y)分子分母同除以xy=(1/x+1/y-1)/(1/x+1/y+1)=(-2-1)/(-2+1)=3
1.已知x+y=-4,xy=3,求5(xy/2+2y)+[6x-(2xy+y-3x)]的值5(xy/2+2y)+[6x-(2xy+y-3x)]=5xy/2+10y+6x-2xy-y+3x=xy/2+9
y分之x=2分之1y=2x所以原原式=(x²-2x²-8x²)分之(x²+4x²+4x²)=-9分之9=-1
原式=-x²y³+3x²y³=2x²y³
(x+2y-3xy)-(-2x-y+xy)=x+2y-3xy+2x+y-xy=(1+2)x+(2+1)y-(3+1)xy=3x+3y-4xy=3(x+y)-4xy=3*1/2-4*(-1/2)=3/2
原式(-xy/3)²*[xy(2x-y)-2x(xy-y²)]=(x²y²/9)(2x²y-xy²-2x²y+2xy²)
1/x-1/y=(y-x)/xy=1y-x=xy(3y-xy-3x)/(x-xy-y)=(3y-y+x-3x)/(x-y+x-y)(2y-2x)/(2x-2y)=-1
原式=3x²y-(2xy-2xy+3x²y+xy)=3x²y-(3x²y+xy)=3x²y-3x²y-xy=-xy=-3×(-1/3)=1
设1/x-1/y=t(5x+xy-5y)/(x-xy-y)=(1-5(1/x-1/y))/(-1-(1/x-1/y))=(5t-1)/(t+1)至于是1/x-1/y=3还是1/y-1/x=3都差不多
x-y分之xy=-3分之1xy分之(x-y)=-3x-y=-3xyx-2xy-y分之2x+3xy-2y=(-6xy+3xy)/(-3xy-2xy)=3/5
x^2-y^2=2xy,得x/y-y/x=2,即(y/x)^2+2(y/x)-1=0∴y/x=-1+√2或y/x=-1-√2(舍去,因为x,y都是正数).即(x-y)/(x+y)=√2-1
y分之x=2分之1y=2x所以原原式=(x²-2x²-8x²)分之(x²+4x²+4x²)=-9分之9=-1
[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy)=[-x²y²+4-4(x²y²-2xy+1)]÷(-xy)=(-x²y²+
分子上应写:(x-1)²或者x²-2x+1再问:怎么书面表达呢?能否详细一些,谢谢再答:希望你及时采纳!!!!!
∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6