已知函数f(x)=x^3+6x^2+15|x|, (1)求f(x)在x=1处的切线方程 (2)求f(x)在[-1,a]上的最小值 好的可加分,急!急!

f'(x)=3x^2+12x+15 (x>0)
f'(1)=3+12+15=30
f(1)=1+6+15=22
切线方程
y-22=30(x-1)
y=30x-8
f'(x)=0
x=1,x=-5
-5<=x<=1
f'(x)<=0
a<=1
最小值
f(a)=a^3+6a^2+15|a|
a>0
最小值
f(1)=1+6+15=22f'(x)=0x=1,x=-5-5<=x<=1f'(x)<=0a<=1最小值f(a)=a^3+6a^2+15|a|a>0最小值f(1)=1+6+15=22 看不懂。解f'(x)的答案不对吧f'(x)=3x^2+12x+15 (x>=0)f'(x)=3x^2+12x-15 (x<=0)f'(1)=3+12+15=30f(1)=1+6+15=22切线方程y-22=30(x-1)y=30x-8f'(x)=3(x+2)^2+3>0 (x>=0)最小值f(0)=0f'(x)=0 (x<=0)x=1,x=-5-5