Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: conjugate (<x>) Returns the complex conjugate of <x>.

(%i1) declare ([aa, bb], real, cc, complex, ii, imaginary);
(%o1) done
(%i2) conjugate (aa + bb*%i); (%o2) aa - %i bb
(%i3) conjugate (cc); (%o3) conjugate(cc)
(%i4) conjugate (ii); (%o4) - ii
(%i5) conjugate (xx + yy);(%o5) conjugate(yy) + conjugate(xx)
(%o1) true (%i2)