if `sum_1^20 r^3 = a ,sum_1^20 r^2 = b` then sum of products of 1,2,3,4,....20 taking two at a time is :

Find the sum of the product of 1,2,3….20 taken two at a time.

Find sum_(r=1)^20 (2r - 1)

sum_(r=1)^(20) r (2r+1)=

If a=sum_(r=1)^oo 1/r^4 then sum_(r=1)^oo 1/((2r-1)^4)=

1,2,3…..sum of 20 term is

If sum_(r=1)^20(r^2+1)r! =k!20 then sum of all divisors of k of the from 7^n, n epsi N is (A) 7 (B) 58 (C) 350 (D) none of these

The sum of the elements of the product [3, 2,0] and [(3),(2), (0)] is

If sum_(r=1)^20(r^2+1)r!=k!20 then sum of all divisors of k of the from 7^n, n epsilin N is (A) 7 (B) 58 (C) 350 (D) none of these

Find the sum, sum_(k=1) ^(20) (1+2+3+.....+k)

Find the sum, sum_(k=1) ^(20) (1+2+3+.....+k)