Finding Roots of a Polynomial

I am trying to write a program that will find the roots of a 4th order polynomial. Basically, I would like to find the roots, T_s, by defining a variable called "Error" and saying something like this:

T_s = 72

Error = "=(1.0*126.8-0.93*1.71e-09*T_s^4)-(88.7)*(T_s-72)"


If Error < 0.0001 Then
ActiveCell = T_s
Else T_s = T_s + 0.01

'I would now like to recalculate the error to see if the new value of T_s meets the convergence criterion'

End If




Does anyone have any suggestions?

Use Solver; T_s = 73.4290165415022