Definite integration yields a strange answer. (Solved)

[parisse]

I think you are in fact confused by the math curriculum of your country. In France, we also teach antiderivatives of fractional powers as a special case of x^alpha, but we give examples of definite integration with positive arguments and that makes really sense because x^alpha=exp(alpha*ln(x)) is not defined if x<0. I can't see any added value in understanding antiderivatives or powers to take negative argument, to the contrary it will just confuse students like you and calculators CAS designed for the US math curriculum must take odd conventions to handle fractional powers.