已（X+Y）²=7,(X-Y)²=3 求X²+Y²=?X*Y=?

若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 2x²-3xy=y²=0（x,y不得o）求x/y+y/x x+y=3,x²+y²=5,求(x-y）^2014 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& 已知x²+y²-8x+6y+25=0,求（x-y+4xy/x-y）（x+y-4xy/x+y） 若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. 已知x+y=1,xy=-二分之一,求x（x+y)(x-y)-x(x+y)² 已知x,y的值满足方程组x+2y=3,x-y=-2,求x/(x-y)²+x²-y²/(x+ 已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y 已知方程组2x+y=6 x-3y=1,求7y（x-3y）²-2（3y-x）³的值 (1)已知x+y=6,x²-y²=5,求x-y的值（2）若x+y=3,x²+y²