Mathematica
Commercial
Wolfram Mathematica (usually termed Mathematica, Mathematica software suite) is a mathematical symbolic computation program.
fxSolver
Free
fxSolver is a math solver for engineering and scientific equations.
Sage
Open Source
Sage offers business management, bookkeeping & accounting software to meet any business need, from small to midsized businesses.
Compare wxMaxima with alternatives
Compare Mathematica and wxMaxima and decide which is most suitable for you.