(I)当a=1时,f′(x)=3x 2-2x,f(2)=14,
曲线y=f(x)在点(2,f(2))处的切线斜率k=f′(2)=8,
所以曲线y=f(x)在点(2,f(2))处的切线方程为8x-y-2=0.
(II).有已知得: a>
x 3 +10
x 2 =x+
10
x 2 ,
设 g(x)=x+
10
x 2 (1≤x≤2) , g′(x)=1-
20
x 3 ,
∵1≤x≤2∴g′(x)<0
所以g(x)在[1,2]上是减函数.
∴ g(x) min =g(2)=
9
2 ,
所以 a>
9
2 .