解方程(1)x²-2x-2=0 (2)2x²-5x-7=0(1)x²-2x-2=0(2)2x²-5x-7=0
问题描述:
解方程(1)x²-2x-2=0 (2)2x²-5x-7=0
(1)x²-2x-2=0
(2)2x²-5x-7=0
答
(1)x²-2x-2=0
x²-2x+1=3
(x-1)²=3
x-1=±√3
x1=1+√3, x2=1-√3
(2)2x²-5x-7=0
1 1
2 -7
(x+1)(2x-7)=0
x1=-1, x2=3.5
答
(1)x²-2x-2=0
x²-2x+1=3
(x-1)²=3
x=1+√3 x=1-√3
(2)2x²-5x-7=0
(2x-7)(x+1)=0
x=7/2 x=-1