配方法F.4

2x²-3x=2
2x²-3x-2=0
x²-(3/2)x-1=0
(x-3/4)²-(3/4)²-1=0
(x-3/4)²-25/16=0
(x-3/4)²=25/16
x-3/4=±5/4
x=-1/2 or x=2

3x²+2x-5=0
x²+(2/3)x-(5/3)=0
(x+1/3)²-(1/3)²-(5/3)=0
(x+1/3)²-16/9=0
(x+1/3)²=16/9
x+1/3=±4/3
x=-5/3 or x=1

y=3x²-6x+2
y=3(x²-2x+2/3)
y=3[(x-1)²-1/3]
y=3(x-1)²-1

y=-2x²-4x-1
y=-2(x²+2x+1/2)
y=-2[(x+1)²-1/2]
y=-2(x+1)²+1

2x²-3x=2
2x²-3x-2=0
（用cross method）
(x-2)(2x+1)=0
x-2=0 or 2x+1=0
x=2 or x=-1/2

3x²+2x-5=0
（用cross method）
(3x+5)(x-1)=0
3x+5=0 or x-1=0
x=-5/3 or x=1

y=3x²-6x+2
△=6²-4(3)(2)
=36-24
=12

y=-2x²-4x-1
△=4²-4(2)(-1)
=16-(-8)
=24

明唔明呀?
唔明我可以再解釋~

1)(x-3/4)^2=25/16
X=3/4+-5/4
X=2 V -1/2

2)(x+1/3)^2=16/9
x=-1/3+-4/3
x=1 V -5/3
3)(x-1)^2=1/3
X=1+-√3
4)2x^2+4x+1
(x+1)^2=-1/2+1^2
x=-1+-√1/2