Your method for finding the CDF is correct(but i didn't check you did the integral properly).
the 10 percentile satisfies:
I need to find 10th percentile of random variable X with PDF defined with:
where is const that should be found too.
By integrating f from 0 to I got cumulative dist. function , so .
First, is this approach OK, and second, how can I calculate required percentile?