xy-30x=3600 xy*80%-30x=1440 x=?y=?
x*-2xy+3y*=9 4x*-5xy+6y*=30
x+2y=xy=30(x>0,y>0),xy的最大值
(-3x^y+2xy)-( )=4x^+xy
由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少?
已知x-xy=8,xy-y=-9,求x+y-2xy的值
已知x-y=4xy,则2x+3xy-2yx-2xy-y
已知xy>0,证明xy+xy/1+x/y+y/x>=4
X²+2xy+y²/xy乘x²-2xy+y²/xy+y²=
1\x+1\y=8\x+y,则y\xy+x\xy=?
x^2+xy+x=36,y^2+xy+y=20,求x+y.
如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值.
X+y=3 xy=-5 Xy=?