`(a+1)(a-1)(a^2+1)` is equals to:

int_(-1)^(1)(x^2+1)dx is equal to

tan^(-1)(1/2)+tan^(-1)(1/3) is equal to

The value of the lim_(n->oo)tan{sum_(r=1)^ntan^(- 1)(1/(2r^2))} is equal to

The sum sum_(n=1)^oo tan^(-1)(3/(n^2+n-1)) is equal to

If 1,alpha,alpha^(2),.......,alpha^(n-1) are the n^(th) roots of unity, then sum_(i=1)^(n-1)(1)/(2-alpha^(i)) is equal to:

(1+2i)/(1+3i) is equal to

cot^(-1)(-1/2)+cot^(-1)(-1/3) is equal to

((1+i)/(1-i))^(2) + ((1-i)/(1+i))^(2) is equal to :

tan^(-1)(1/(11))+tan^(-1)(2/(11)) is equal to (a) 0 (b) 1//2 (c) -1 (d) none of these

The value of lim_(xrarr1)Sigma_(r=1)^(10)=(x^(r )-1^(r ))/(2(x-1)) is equal to