power documentation Power Expand ExpandAll Log Sqrt I PolynomialQ Exponent Coefficient CoefficientList PolynomialQuotientRemainder PolynomialQuotient PolynomialRemainder FactorTermsList FactorTerms ExpreduceFactorConstant Variables PolynomialGCD SquareFreeQ FactorSquareFree Arg ComplexExpand Exp Conjugate