- #1
physics604
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- 2
Homework Statement
Find the derivative of y=cos(a3+x3)
Homework Equations
Chain rule
The Attempt at a Solution
y=cosu
[itex]\frac{dy}{du}[/itex] = -sinu
u=a3+x3
[itex]\frac{du}{dx}[/itex] = 3a2+3x2
[itex]\frac{dy}{dx}[/itex] = -3sin(a3+x3)(a2+x2).
The answer is supposed to be -3x2sin(a3+x3). What did I do wrong?
Any help is much appreciated.