With 2 in A1, 3 in A2, and any value for t in cell A3, in another cell -say, A4 - use the formula

=A1*A3+A2*A3^0.2

and the desired value in cell B

Then use solver like this in a macro

Sub Macro1()

SolverOk SetCell:="$A$4", MaxMinVal:=3, ValueOf:=Cells(1, 2).Value, ByChange:="$A$3", Engine:= _

1, EngineDesc:="GRG Nonlinear"

SolverSolve

SolverFinish KeepFinal:=True

End Sub

You will need to set a reference to Solver in your project, and have the add-in installed in your Excel settings.