How to calculate fractional powers of negative numbers in Ruby?

Question

I want to expand my previous question and ask about calculating any fractional powers of negative numbers? I mean only real roots. What rules or techniques are used to solve this problem?
https://www.sololearn.com/discuss/1191119/?ref=app

Answer 1

Use this code
Gets/Gets = x0
Gets = a
Gets = b
(a+b) = e
Puts e