Question

数学，，，，

Answer 1

用配方法解方程:

1).x^2-x-1=0
(x^2-x+1/4)-1/4-1=0
(x-1/2)^2=5/4
x-1/2= ±√5/2
x=1/2 ±√5/2
2).3x^2-9x+2=0
3(x^2-3x+9/4)-27/4+2=0
3(x-3/2)^2=19/4
(x-3/2)^2=19/12
x-3/2= ±√57/6
x=3/2±√57/6
用适当的方法解方程:

1). 3(x+1)^2=12
(x+1)^2=4
x+1=±2
解得x=1 or x=-3
2).y^2+4y+1=0
(y^2+4y+4)-4+1=0
(y+2)^2=3
y+2=±√3
y=-2±√3
3). x^2-8x=84
x^2-8x+16=84+16
(x-4)^2=100
x-4=±10
解得x=14 or x=-6
4).y^2+3y+1=0

y=[-3±√(9-4)]/2
=-3/2±√5/2

Answer 2

3(x-1)²=12
(x-1)²=4
x-1=±2
x1=3,x2=-1
y²+4y+1=0
(x+2)²=3
x+2=±根号3
x=-2±根号3