# Solve system of equations after one variable

Posted 9 years ago
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 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*eSolve 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!
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Posted 9 years ago
 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= {{a -> ConditionalExpression[d e, b - c d e == 0]}} *)You now get the solution and the condition in "parameter" variables that must be satisfied.
Posted 9 years ago
 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]