If `sum_(r=0)^(10)((r+2)/(r+1)).^n C_r=(2^8-1)/6` , then `n` is (A) 8 (B) 4 (C) 6 (D) 5

If sum_(r=0)^n(2r+3)/(r+1), C_r=((n+k)*2^(n+1)-1)/(n+1) then 'k' is

sum_(r=0)^(n)((r+2)/(r+1))*""^(n)C_(r) is equal to :

If sum_(r=1)^(n)r^(3)((C(n,r))/(C(n,r-1)))=14^(2) then n=

If sum_(r=0)^(n-1)((^nC_(r))/(nC_(r)+^(n)C_(r+1)))^(3)=(4)/(5) then n=

The value of sum_(r=0)^(10)r(C(n,r))/(C(n,r-1))=

If a=sum_(r=1)^oo(1/r)^2, b=sum_(r=1)^oo1/((2r-1)^2), then a/b= (A) 5/4 (B) 4/5 (C) 3/4 (D) none of these

sum_(r=0)^n((-1)^r*C_r)/((r+1)(r+2)(r+3))=1/(a(n+b)), then a+b is

Given S_(n)=sum_(r=0)^(n)(1)/(2^(r)),S=sum_(r=0)^(oo)(1)/(2^(r)). If S-S_(n)<(1)/(1000), then least value of ln'(A)8 (B) 9(C)10(D)11