已知x²+2x-y²+6y-8=0,且x+y不等于2,求x-y的值
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已知x²+2x-y²+6y-8=0,且x+y不等于2,求x-y的值
已知x²+2x-y²+6y-8=0,且x+y不等于2,求x-y的值
已知x²+2x-y²+6y-8=0,且x+y不等于2,求x-y的值
x²+2x-y²+6y-8=0
配方得
(x+1)^2-(y-3)^2=0
(x+1+y-3)(x+1-y+3)=0
x+y≠2
x+1-y+3=0
x-y=-4
(x²+2x+1)-(y²-6y+9)=0
(x+1)²-(y-3)²=0
(x+1)²=(y-3)²
则:
x+1=y-3或x+1=-(y-3)
x-y=-4或x+y=2【舍去】
则:
x-y=-4
x²+2x-y²+6y-8=0
x²+2x+1-y²+6y-9=0
(x+1)²-(y-3)²=0
(x+1+y-3)(x+1-y+3)=0
(x+y-2)(x-y+4)=0
∵x+y不等于2
∴x-y+4=0
∴x-y=-4已知三角形的三边长a、b、c满足a²+b...
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x²+2x-y²+6y-8=0
x²+2x+1-y²+6y-9=0
(x+1)²-(y-3)²=0
(x+1+y-3)(x+1-y+3)=0
(x+y-2)(x-y+4)=0
∵x+y不等于2
∴x-y+4=0
∴x-y=-4
收起
原式=(x-y)(x+y)+2x+6y=8