Question

用配方法解下列一元二次方程 (1)y²-6y+6=0 (2)x²-2x-1=0 (3)x

用配方法解下列一元二次方程
(1)y²-6y+6=0
(2)x²-2x-1=0
(3)x²+5x-6=0
(4)2x²-7x-4=0

Answer 1

1）y²-6y+9-3=0
(y-3)²=3
y-3=±√3
y=3±√3

2) x²-2x+1-2=0
(x-1)²=2
x-1=±√2
x=1±√2

3) x²+2*5x/2+25/4=6+25/4
(x+5/2)²=49/4
x+5/2=±7/2
x=-5/2±7/2
x=-6, 1

4)x²-7x/2=2
x²-2*7x/4+(7/4)²=2+49/16
(x-7/4)²=81/16
x-7/4=±9/4
x=7/4±9/4
x=4, -1/2