derivative

oded244

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Oct 4, 2007
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38
how do i solve:

2007921_1622815457_444.JPG
 
#1: product rule. Rewrite as \(\displaystyle \L\\\underbrace{x^{4}}_{\text{f(x)}}\overbrace{(x+1)^{-4}}^{\text{g(x)}}\)

\(\displaystyle \L\\f(x)g'(x)+g(x)f'(x)\)

\(\displaystyle \L\\\underbrace{x^{4}}_{\text{f(x)}}\overbrace{(-4)(x+1)^{-5}}^{\text{g'(x)}}+\underbrace{(x+1)^{-4}}_{\text{g(x)}}\overbrace{(4x^{3})}^{\text{f'(x)}}\)

Now simplify.

#2: Same as above. product rule.
 
well, i understand the product rule and the chain rule but i have a problem when they both in the same derivative
first one i understood, the second one im still trying to figure out.
 
Since you understand the product rule, you must use a little chain rule on it also. Remember, derivative of inside times derivative of outside.

The second part is just:

Derivative of outside: \(\displaystyle \L\\3(5x-1)^{2}\)

Derivative of inside is just 5

So, you have: \(\displaystyle \L\\3(5x-1)^{2}(5)=15(5x-1)^{2}\)

Now, combine it with the other steps and you have it.
 
^^ thats what i got but the answear in the book is:
x^3(5x-1)^2 (35x-4)
 
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