已知xy满足2分之x 1=4分之y 3-搜答案-搜搜考试网

解题思路：根据两个非负数的和必然两个都等于0进行计算解题过程：解：因为，，所以.解得.所以

-5分之2

因为3x+4

因为x-y=4xy所以x-2xy-y=2xy2x+3xy-2y=11xyx-2xy-y分之2x+3xy-2y=5.5

xy=6/(x+y)xy(x+y)=6,已知x和y是整数,则xy和(x+y)也是整数,而6=2*3=1*6当xy=3时,x+y=2,无整数解当xy=1时,x+y=6,无整数解当xy=6时,x+y=1,

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

x方+y方+5/4=2x+y(x方-2x+1)+（y方-y+1/4)=0(x-1)方+（y-1/2)方=0x=1,y=1/2xy/(x+y)=1/3

(√x-√y)²+4√(xy)=(√x+√y)²x=2/5y=8/5√(xy)=4/5√x+√y=√(2/5)+2√(2/5)=3√(2/5)(√x+√y)²/[x+√(

x分之1-y分之1=4(xy)分之(y-x)=4y-x=4xyx-y=-4xy(x-2xy-y)分之(2x+xy-2y)=[(x-y)-2xy]分之[2(x-y)+xy]=(-4xy-2xy)分之(-

x^2+y^2+5/4=2x+y(x-1)^2+(y-1/2)^2=0x=1,y=1/2xy/(x+y)=1*(1/2)/(1+1/2)=1/3

【x+y】分之xy=-2,xy分之【x+y】=-1/21/x+1/y=-1/2(1)【y+z】分之yz=3分之4,yz分之【y+z】=3/41/y+1/z=3/4(2)【z+x】分之zx=-3分之4,

把要求的式子分子分母同时除以xy得(x+2xy+y)/(3x-4xy+3y)=(1/y+2+1/x)/(3/y-4+3/x)=(2+3)(3×3-4)=1

已知xy满足x²+y²+5/4(四分之五)=2x+y,求代数式(x+y)xyx²+y²+5/4=2x+yx²-2x+1+y²-y+1/4=0

由已知条件可得：x-y=-4xy,（也就是在等式两边乘xy后整理,即可）,代入所求的式子里分母为-4xy+7xy,即3xy；分子为-4xy-2xy,即-6xy,化简得-2

将x^2+y^2+5/4=2x+y化为将x^2-2x+1+y^2-y+1/4=0即(x-1)^2+(y-1/2)^2=0上面的等式成立,则有x-1=0且y-1/2=0即x=1,y=1/2所以xy/(x

x/3-y/4=3x+2y==>4x-3y=36x+24y==>①32x=-27y==>x=-27y/32②(4x-3y)^2=(36x+24y)^2②==>16x^2+9y^2-24xy=1296x

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

等于0?(x+2y)^2-x-2y+1/4=0(x+2y-1/2)^2=0x+2y-1/2=0x+2y=1/2

x1+x2=-3/2x1x2=-21/x1+1/x2=（x1+x2)/x1x2=(-3/2)/(-2)=3/4x1²+x2²=(x1+x2)²-2x1x2=(-3/2)&

x1+x2=4x1x2=-1(x1+x2)^2/(1/x1+1/x2)=(x1+x2)^2*x1x2/(x1+x2)=x1x2*(x1+x2)=-4