limit x tends to 0,(1-x)n-1/x
lim x>0(1-x)n-1/x
limx>0(1-nC1x +nC2x2 -nC3x3 +........... -1)/x
limx>0(1-nx/1! +n(n-1)x2/2! -n(n-1)(n-2)x3/3! .............. -1)/x
limx>0 - n+n(n-1)x -n(n-1)(n-2)x2 ................ cancelling x from numerator and denominator,
= -n
limx>0(1-nC1x +nC2x2 -nC3x3 +........... -1)/x
limx>0(1-nx/1! +n(n-1)x2/2! -n(n-1)(n-2)x3/3! .............. -1)/x
limx>0 - n+n(n-1)x -n(n-1)(n-2)x2 ................ cancelling x from numerator and denominator,
= -n
