Getting "Bad solve variable." when trying to solve simple implicit derivative using Mathcad Prime 9

[FS_10134255]

I'm trying so solve an implicit differentiation example but I keep getting bad solve variable error

This is my example:

x^2+y^2=25

[terryhendicott]

Hi,

[FS_10134255]

Hi,

I used it as an example to be able to do implicit differentiation for a simple equation. I was able to get the answer you got but I would like to solve for y' or dy/dx. I have a more complicated equation that I need to differentiate. 

[Werner_E · Accepted solution]

Could it be that you are either looking for this

or this

or are you really looking for an explicit expression for y'(x)

The 'simplify' modifier isn't necessary in case of this expression and was just used out of habit.
And of course you also can omit the "-25" because the derivative of a constant is zero anyway.

[FS_10134255]

The third option is what I was looking for. Thanks!