`tan^-1 x + tan^-1y= tan^-1 (frac{x+y}{1-xy})`.

tan^-1 x - tan^-1 y= tan^-1 (frac{x-y}{1+xy} .

Write down the conditioni under which tan^-1 x + tan^-1 y = tan^-1 (x+y)/(1-xy), x, y in r .

Solve: tan^-1 (x+2) + tan^-1 (x-2) = tan^-1 (frac{4}{19}), x>0

Solve for x: tan^-1 (x+1) + tan^-1(x-1) = tan^-1 frac{8}{31}, x > 0

Solve: tan^-1 (x+3) + tan^-1 (x-3) = tan^-1 (frac{4}{39}), x>0

Solve: tan^-1 (x+4) + tan^-1 (x-4) = tan^-1 (frac{4}{67}), x>0

tan^-1 frac{1}{2} + tan^-1 frac {1}{7} = tan^-1 frac{9}{13}

Solve for x , tan^(-1) ( x + 1) + tan^(-1) x + tan^(-1) ( x - 1) = tan ^(-1) 3x

tan^-1 frac{1}{2} + tan^-1 frac {2}{11} = tan^-1 frac{3}{4}

Let tan^(-1) y = tan^(-1) x + tan^(-1) ((2x)/(1 -x^(2))), " where " |x| lt (1)/(sqrt3) . Then a value of y is