Well hmm, i'll give you an idea you do the rest.
Say we want to give a partition of [0,2] in 7 subintervals of equal length.
First you need to know the length of the the original, in this case it would be 2.
So if i want to divide it in 7 parts, each part needs to have length: 2/7
So... the partition would be:
What about your interval?
(Obs: The function f plays no role in finding a partition of equal length, UNLESS you need something else like piecewise-continuous or what ever.)