Hello,
Im new to Mathematica and i didnt find the answer to my question in the help.
Its an easy one:
I have to equations with one identical variable, which i want to equalize and solve for another variable.
For example:
a=b/c
a=d*e
Solve these two equations for e.
Solution would be: e=b/(c*d).
My calculator TI89Titanium does this automatically, but when i try to use the Solve[…,e] function in Mathematica the solution is: {}
Thanks in advance!
The first thing you want to do is elimiate a from the system of equations. This can be done with Eliminate:
Eliminate[{a == b/c, a == d*e}, a]
After that, you can use Solve. Together they are:
Solve[Eliminate[{a == b/c, a == d*e}, a], e]
The result is only conditionally correct, and, per documentation, `Solve` by default does not return nongeneric solutions. To get it you could do:
Solve[{a == b/c, a == d*e}, a, MaxExtraConditions -> 1]
(* Out[62]= {{a -> ConditionalExpression[d e, b - c d e == 0]}} *)
You now get the solution and the condition in “parameter” variables that must be satisfied.