Applying Product Rule

JSmith

Junior Member
Joined
Sep 21, 2012
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120
Given the function
showimage
.
a) Determine the intervals of increase and decrease.
b) Determine the absolute minimum value of f(x).

So obviously I have to find the derivative and calculate the critical numbers, then test them and so on....

But what I am stuck on is applying the product rule to the function ex. I know its derivative is itself, so:


f(x)=x3ex
f'(x)=(x3)(ex)+(ex)(3x2)

then how do I simplify?
 
You want to factor so that you may apply the zero-factor property. What is the greatest factor you see common to both terms?
 
You want to factor so that you may apply the zero-factor property. What is the greatest factor you see common to both terms?

would it be x2​? or ex??? the greatest factor common to all four terms, or the product of the two sets of terms?
 
Your derivative has two terms, and each term consists of factors:

\(\displaystyle f'(x)=x^3e^x+3x^2e^x\)

What is the largest factor common to both terms?
 
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