# Chain rule

What did I do wrong?

1. Find f'(x) when f(x)= 5x(sinx + cosx)

My answer: cos(4x^2)- sin(6x^2)/(5x^2)

2. Find f'(x) when f(x)= ((x^3) + 4x + 4))^2

My answer: 6x^2(x^3 + 4x + 4)

3. Find f'(x) when f(x)= (3x + 8)^-3

My answer: -6(3x + 8)

4. Find f'(x) when f(x)= Sq root of (5x + 8)

My answer: x/5x + 8

5. Find f'(x) when f(x)= cos(3x + 2)

My answer: ?

6. Find f'(x) when f(x)= sin(cos(x^5))

My answer: ?

https://brainmass.com/math/calculus-and-analysis/chain-rule-derivatives-hw-3176

#### Solution Preview

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Problem:

What did I do wrong?

1. Find f'(x) when f(x)= 5x(sinx + cosx)

My answer: cos(4x^2)- sin(6x^2)/(5x^2)

2. Find f'(x) when f(x)= ((x^3) + 4x + 4))^2

My answer: 6x^2(x^3 + 4x + 4)

3. Find f'(x) when f(x)= (3x + 8)^-3

My answer: -6(3x + 8)

4. Find f'(x) when f(x)= Sq root of (5x + 8)

My answer: x/5x + 8

5. Find f'(x) when f(x)= cos(3x + 2)

My answer: ?

6. Find f'(x) when f(x)= sin(cos(x^5))

My answer: ...

#### Solution Summary

This shows six examples of derivatives using chain rule