winterrose
New member
- Joined
- Oct 11, 2013
- Messages
- 6
Hello so stuck here, could use some help.
Given f(x)=(x^4)(e^-x)
Step 1) Find f'(x)
Step 2) Find f"(x), this is where I am having trouble
Step 3) Find f"(x)=0
So I set e^-x=0 and x^4-4x^3-4x+4=0, to find where f"(x)=0
e^-x=0
x=0
x^4-4x^3-4x+4=0
(I am at a lost on how to solve this part)
My first attempt is [x^3(x-4)-4(x+1)] not sure if that does anything. My algebra is a little rusty, and it is probably something silly but I could use any suggestion, cheers.
Given f(x)=(x^4)(e^-x)
Step 1) Find f'(x)
- f'(x)=x^4+(4x)e^-x
Step 2) Find f"(x), this is where I am having trouble
- f"(x)=(e^-x)(x^4-4x^3-4x+4)
Step 3) Find f"(x)=0
So I set e^-x=0 and x^4-4x^3-4x+4=0, to find where f"(x)=0
e^-x=0
x=0
x^4-4x^3-4x+4=0
(I am at a lost on how to solve this part)
My first attempt is [x^3(x-4)-4(x+1)] not sure if that does anything. My algebra is a little rusty, and it is probably something silly but I could use any suggestion, cheers.