denoting infinity by i
ANSWER TO lim nCr p^rq^(n-r) =c] [e^(-m)( m^r)]/ r!
n->i
lim nCr p^rq^(n-r)
n->i
lim n!/((n-r)!*r!) p^rq^(n-r)
n->i
now using np=m, p+q=1 where m ,r are constants
lim n!/((n-r)!*r!) (m/n)^r*{1-(m/n)}^(n-r)
n->i
lim n!/((n-r)!*r!)* [(m/n)^r*{1-(m/n)}^n )/(1 - ( m/n))^r
n->i
lim {1-(m/n)}^n = e^(-m)
n->i
when n->i { [n!/(n-r)!]/n^r} becomes 1
therefore we get {e^(-m)*m^r}/r!
ANSWER TO lim ( n!/(n^n))^(1/n) =d] 1/e
n->i
let y= ( n!/(n^n))^(1/n)
log y = [log n! -nlogn]/n
n!=n*(n-1)*(n-2)......3*2*1
log n!=logn +log(n-1) +log(n-2)+.......
log n= logn +logn+......ntimes
NOW USING THE FORMULA OF SERIES REPRESENTED BY DEFINITE INTEGRALS WHEN n TENDS TO INFINITY
lim log y = SIGMA log(1- (r/n)) WITH r varying from 0 to n
n->i n->i
which when converted gives
INTEGRATION OF log(1-x) with limits from 0 to 1
where x=(r/n)
INTEGRATION gives -1
ANTILOG OF -1 IS 1/e { we take antilog as we have taken log y)