Hi comrades. I am trying to do something like this
plot3d( fsolve( x^2 + a*x + b =0, x), a=0.1..5, b=0.5..3);
(this is not what I'm actually doing, I want to make a 3D plot of a more complicated function that uses fsolve, so don't just suggest the quadratic formula!).

I.e. plot the root of an equation as a function of some parameters in the equation.

It's not plotting because it says
"Error, (in fsolve) {a, b} are in the equation, and are not solved for"