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=
x2+2x+1写成y=a(x-h)2+k的形式是( )1 2
A. y=
(x-1)2+21 2
B. y=
(x-1)2+1 2
1 2
C. y=
(x-1)2-31 2
D. y=
(x+2)2-1 1 2
答
y=
x2+2x+1=1 2
(x2+4x+4)-2+1=1 2
(x+2)2-11 2
故选D.