(1).当x=2、y=—1时,求3x(x²y—xy²)—2x²(½xy+y
当x=2,y=-1时,求代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
若x=1/2,y=1 求x(x²+xy+y²)-y(x²+xy+y²)+3xy(
1/x+1/y=5,求2x-3xy+2y/x²+xy+y的值
|x+2|+(y-1/4)²=0,求2(x²y+xy)-3(x²y-xy)-4x²
先化简,再求值:3x²—[2x²y—(xy—x²)]+4x²y,其中x=—1,y
已知x+y=3 xy=-5 求x设abc=1 求x²+3xy+2y²/x²y+2xy
已知2X-3√xy-2y=0(x>0)求2x²+xy-9y²分之x²+4xy-16y
(1)当1\x-1\y=3时求2x+3xy-2y\x-2xy-y的值
已知x-2y=3,x²-2xy+4y²=11,求下列各值; (1)xy (2)x²-2xy
x(x-1)-(x平方-y)=-3,求x平方+y平方-2xy
已知X²+Y²+X²Y²-4XY+1=0 求:(X-Y)^2008-(XY)^2
已知x+y=2,xy=1/2,求x³y+2x²y²+xy³