1.
x^2+4x+2=0
x^2+4x+4=2
(x+2)^2=2
x=-2±√2
2.
x^2-2x-3=0
(x-3)(x+1)=0
x=3或x=-1
x²+4x+2=0
x²+4x+4=2
(x+2)²=2
x+2=±√2
x=-2-√2,x=-2+√2
x²-2x-3=0
(x-3)(x+1)=0
x=3,x=-1
。x²+4x+2=0 解: x²+4x=0+2
x²+4x=2
4x=2
x=0.5
x²-2x-3=0
(x-3)(x+1)=0
x=3,x=-1
x²+4x=2
4x=2
x=0.5