若2.5x=1000,0.25y=1000,则1x−1y
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
若全集I={(x,y)|x,y∈R},集合M={(x,y)|(y-3)/(x-2)},N{(x,y)|y=x=1},则(
1.已知1/x+1/y=-1/x+y,则y/x+x/y=?
若x-y=1,求代数式x(x-y)+y(y-x)+2013的值
若2.5的x次方=1000,0.25的y次方=1000 则1/x-1/y=?什么
若2.5的x次方=1000,0.25的y次方=1000,则1/x-1/y等于?
若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y=
若7x+10y分之5x+y=1/2,则x/y=
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
数学题,相反数1.x与y互为相反数,则x+y=( )2.若x-y=1,那么-(y-x)=( ),-(y-x)-1=( )
若实数x,y满足2x*X+3y*y=1,S=3x*x-2y*y,则S的取值范围为
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )