What is the value of the following expression? `1/((2^2-1))+1/((4^2-1))+1/((6^2-1))+\ +1/((20^2-1))` `9/(19)` (b) `(10)/(19)` (c) `(10)/(21)` (d) `(11)/(21)`

What is the value of the following expression? (1)/((2^(2)-1))+(1)/((4^(2)-1))+(1)/((6^(2)-1))+backslash+(1)/((20^(2)-1))(9)/(19) (b) (10)/(19)(c)(10)/(21) (d) (11)/(21)

Find: 1(10)/(21)+2(1)/(6)

Find the value of 1-((1(2)/(3))/(3(1)/(2))+(1(1)/(6))/(3(1)/(2)))* a) (3)/(20) (b) (4)/(21)(c)(8)/(21) (d) (13)/(21)

The value of cot sum_(n=1)^(19)(cot^(-1)(1+sum_(p=1)^(n)2p)) is equal to (a) (21)/(19) (b) (19)/(21) (c) -(19)/(21) (d) -(21)/(19)

The value of cotsum_(n=1)^(19)cot^(-1)(1+sum_(p=1)^(n)2p) is equal to (a) (21)/(19) (b) (19)/(21) (c) -(19)/(21) (d) -(21)/(19)

The value of cot sum_(n=1)^(19)(cot^(-1)(1+sum_(p=1)^(n)2p)) is equal to ( a )(21)/(19) (b) (19)/(21)(c)-(19)/(21) (d) -(21)/(19)

The value of the determinant |(-(2^5 + 1)^2,2^10 -1,1/(2^5-1)),(2^10-1,-(2^5-1)^2,1/(2^5+1)),(1/(2^5-1),(1/(2^5+1),-1/(2^10-1)^2) )|

The 15th term of the series 2 1/2+1 7/(13)+1 1/9+(20)/(23)+.... i s (10)/(39) b. (10)/(21) c. (10)/(23) d. none of these