函数y=12x2+2x+1写成y=a(x-h)2+k的形式是(  ) A.y=12(x-1)2+2 B.y=12(x-1)2+12 C.y=12(x-1)2-3 D.y=12(x+2)2-1

问题描述:

函数y=

1
2
x2+2x+1写成y=a(x-h)2+k的形式是(  )
A. y=
1
2
(x-1)2+2
B. y=
1
2
(x-1)2+
1
2

C. y=
1
2
(x-1)2-3
D. y=
1
2
(x+2)2-1

y=

1
2
x2+2x+1=
1
2
(x2+4x+4)-2+1=
1
2
(x+2)2-1
故选D.