x2-x-y2-y 解法：=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)后半部的解法（x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的

二元二次方程组：(X2+X2/2=Y2 X/2+X+Y=6)解法 x2+x+y2/x+y x2+y2=208(x-y) (x-y)(x2+xy+y2) (x+y)(x2-xy+y2) X2y2-x2-y2+1 =x2(y2-1)-(y2-1) =(y2-1)(x2-1) =(y+1)(y-1)(x+1)(x-1) 中的=x2(y2-1)-(y2-1) =(y2-1)(x2-1是怎么算出来的? x2-2xy+y2=4 x2+y2-x-y=6 解不等式x2-2xy+y2=4 x2+y2-x-y=6 解不等式 已知x,y满足（x2+y2）(x2+y2-1)=2,则x2+y2的值为多少?x2,y2表示x和y的平方 2010.09.已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值 已知实数x.y满足（x2+y2）（x2+y2-1）=2,求x2+y2的值 x2+y2+x+y=18 x2+y2-2x-4x=24 解方程组 y=x+√(1-x2) y2=x2+(1-x2)+2x√(1-x2) 我做对了吗.x2(x-y)+y2(y-x)= x2(x-y)-y2(x-y)=x2-y2=(x+y）（x-y） 解方程组①x2-y2=3x+3y②x2-xy+y2=27 方程组 x2+y2+x+y=18 x2+xy+y2=19 已知x2-y2=20,x+y=4,则x2+y2的值是多少? x2+y2=1和x2+y2-4x+2y=4解这组方程, 已知x2-y2=8,x-y=2,求x2+y2的值