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

sum_(r=1)^(n)(1)/((r+1)(r+2))*^(n+3)C_(r)=

Statement -2: sum_(r=0)^(n) (-1)^( r) (""^(n)C_(r))/(r+1) = (1)/(n+1) Statement-2: sum_(r=0)^(n) (-1)^(r) (""^(n)C_(r))/(r+1) x^(r) = (1)/((n+1)x) { 1 - (1 - x)^(n+1)}

Statement -2: sum_(r=0)^(n) (-1)^( r) (""^(n)C_(r))/(r+1) = (1)/(n+1) Statement-2: sum_(r=0)^(n) (-1)^(r) (""^(n)C_(r))/(r+1) x^(r) = (1)/((n+1)x) { 1 - (1 - x)^(n+1)}

sum_(r=0)^(n)((n-3r+1)^(n)C_(r))/((n-r+1)2^(r)) is equal to

The value of sum_(r=1)^(n)(-1)^(r-1)((r )/(r+1))*^(n)C_(r ) is (a) 1/(n+1) (b) 1/n (c) 1/(n-1) (d) 0

The value of sum_(r=1)^(n)(-1)^(r-1)((r )/(r+1))*^(n)C_(r ) is (a) 1/(n+1) (b) 1/n (c) 1/(n-1) (d) 0

Assertion: If n is an even positive integer n then sum_(r=0)^n ("^nC_r)/(r+1) = (2^(n+1)-1)/(n+1) , Reason : sum_(r=0)^n ("^nC_r)/(r+1) x^r = ((1+x)^(n+1)-1)/(n+1) (A) Both A and R are true and R is the correct explanation of A (B) Both A and R are true R is not te correct explanation of A (C) A is true but R is false. (D) A is false but R is true.