若（x+y)(1-x-y)+6=0,则x+y的值是 A .2 B.-3 C.-2或3 D.2或-3

若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若（x+y)(1-x-y)+6=0,则x+y的值是_____ 已知4x+6y=1 若x=y 则x,y的值等于?若x+y=0 则x=?y=? 若实数X,Y满足X²+Y²+4X-2Y +1=0,则X²-6X+Y²-2Y的最大值是多少 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= （5x-6y)(x+y)=0(x不等于y),则y/x= 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 证明：若x>0,y>0,x+y=1,则（x+1/x)(y+1/y)≥25/4 若x^2+y^2-6x+8y+25=0 则y/x-x/y的值是 若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y= 若x,y满足|x-y+1|+(x+y+3)^2=0则x^2-y^2= 若x>0,y>0,且x-根号xy=6y,则x/y= 若x^2+y^2-10x+6y+34=0,则x+y=? 若x^2+2x+y^2-6y+10=0,则x-y 若|x+y+1|+(x-2y)的平方=0,则x+2y=? 若|x+y-5|+(x-y+1)²=0,则x²-y²= 一元二次方程,(x+y)(1-y-x)+6=0,则√-(x+y)=? 若(x^+y^)(x^+y^-1)=6,则x^+y^的值为