" If "S_(n)=2n^(2)+3n" then "d=dots dots

If S_(n) is the sum of the first n terms of an A.P. then : (a) S_(3n)=3(S_(2n)-S_n) (b) S_(3n)=S_n+S_(2n) (c) S_(3n)=2(S_(2n)-S_(n) (d) none of these

Divide the sum of (-13)/5\ a n d(12)/7 by the product of (-31)/7\ a n d(-1)/2dot

If S_1 be the sum of (2n+1) term of an A.P. and S_2 be the sum of its odd terms then prove that S_1: S_2=(2n+1):(n+1)dot

Prove that [(n+1)//2]^n >(n !)dot

Prove that [(n+1)//2]^n >(n !)dot

If f(x)=|x^nn !2cosxcos(npi)/2 4sinxsin(npi)/2 8| then find the value of (d^n)/(dx^n)([f(x)])_(x=0)dot(n in z)dot

If f(x)=|x^nn !2cosxcos(npi)/2 4sinxsin(npi)/2 8| then find the value of (d^n)/(dx^n)([f(x)])_(x=0)dot(n in z)dot

Consider the sequence defined by a_n=a n^2+b n+c dot If a_1=1,a_2=5,a n da_3=11 , then find the value of a_(10)dot

(n!) / ((nr)!) = n (n-1) (n-2) dots (n- (r-1))