502. The sum `sum_(r=1)^50 r.(2^r+2^(50-r))` equals

The sum sum_(i=1)^(50)(r) is :-

The sum sum_(r=1)^(10)(r^(2)+1)xx(r!) is equal to

The sum sum_(r=2)^(oo)(1)/(r^(2)-1) is equal to

sum_(r=0)^(20).^(50-r)C_6

The value of sum sum_(r=1)^(10)(2^(r-1)+8r-3) is equal to :

If sum_(r=1)^(n) t_(r ) = sum_(k=1)^(n) sum_(j=1)^(k) sum_(i=1)^(j) 2 , then sum_(r=1)^(n) (1)/( t_(r )) equals :

The value of sum_(r=0)^50 (.^(100)C_r.^(200)C_(150+r)) is equal to

The value of sum_(r=0)^(50)(-1)^r((50)C_r)/(r+2) is equal to a . 1/(50xx51) b. 1/(52xx50) c. 1/(52xx51) d. none of these

The value of sum_(r=0)^(50)(-1)^r((50)C_r)/(r+2) is equal to a . 1/(50xx51) b. 1/(52xx50) c. 1/(52xx51) d. none of these