1.√[(x-1)²+y²]=|x+1|
[(x-1)²+y²]=(x+1)²
x²-2x+1+y²=x²+2x+1
y²=4x
2.|√[(x-2)²+y²]-√[(x+2)²+y²|=2
当√[(x-2)²+y²] ≥√[(x+2)²+y²]时
|√[(x-2)²+y²]-√[(x+2)²+y²|=2
√[(x-2)²+y²]=√[(x+2)²+y² ] +2
[(x-2)²+y²]=[(x+2)²+y² ] +4+4√[(x+2)²+y² ]
-x-1=√[(x+2)²+y² ]
y²=-2x-3
当√[(x-2)²+y²]﹤√[(x+2)²+y²时
|√[(x-2)²+y²]-√[(x+2)²+y²|=2
√[(x+2)²+y²]=√[(x-2)²+y² ] +2
[(x+2)²+y²]=[(x-2)²+y² ] +4+4√[(x-2)²+y² ]
x-1=√[(x-2)²+y² ]
(x-1)²=[(x-2)²+y² ]
y²= 2x-3