若a>0,b>0,且函数f(x)=4x3﹣ax2﹣2bx﹣2在x=1处有极值,则ab的最大值( )
A:2
B:3
C:6
D:9
A. It's very hot.
B. Three little pigs are fat.
C.I have a good idea.
D. Open the door.
E. We are good brothers.
(x+1)4的展开式中x2的系数为
二次函数y=(x-2)2+1的图象的顶点坐标是( )