M, n and p are all integrals on symmetric intervals, and the parity of the integrand function is mainly considered.

The integrand in (1)M is odd function, so M=0.

(2) The integrand function in NP has no parity, but a single part in NP has parity, so we compare the size relationship between n and p by difference, and merge the odd function part and the even function part. Get N>P

(3) In the same way, treat P. The first half of the integrand in P is odd function and the second half is even, so we can also get P>0, so N>P>M.