# Math Help - Derivative

1. ## Derivative

Guys, is this right?
And if it is, from the the y' got in there?

2. $\begin{array}{lcl}z & = & \sin \frac{1}{y} \\ z' & = & \underbrace{\left(\cos \frac{1}{y}\right) \cdot \left(\frac{1}{y}\right)'}_{\text{By chain rule}} \end{array}$
etc. etc.

y' shouldn't be there.

3. y' should be there only if you are differentiating with respect to a variable except y.