# I'm going to need some assistance with this one..

#### wjm11

##### Senior Member
Use implicit differentiation with respect to t on your starting equation, then plug in the given values. You weren't given a value for z, so your solution for dz/dt will still have a z in it.

#### kitkalin

##### New member
Use implicit differentiation with respect to t on your starting equation, then plug in the given values. You weren't given a value for z, so your solution for dz/dt will still have a z in it.
Did I do this right?

#### wjm11

##### Senior Member
Almost right; error on the left hand side: d(z^2)/dt = 2z(dz/dt)

Final solution: dz/dt = 0/2z = 0 (where z does not equal zero; note: it's already given that z is positive.))