$$\lim_{x \to \frac{\pi}{4}^-}\left(2 \tan{\left(x \right)}\right) = 2$$ More at x→pi/4 from the left $$\lim_{x \to \frac{\pi}{4}^+}\left(2 \tan{\left(x \right)}\right) = 2$$ $$\lim_{x \to \infty}\left(2 \tan{\left(x \right)}\right)$$ More at x→oo $$\lim_{x \to 0^-}\left(2 \tan{\left(x \right)}\right) = 0$$ More at x→0 from the left $$\lim_{x \to 0^+}\left(2 \tan{\left(x \right)}\right) = 0$$ More at x→0 from the right $$\lim_{x \to 1^-}\left(2 \tan{\left(x \right)}\right) = 2 \tan{\left(1 \right)}$$ More at x→1 from the left $$\lim_{x \to 1^+}\left(2 \tan{\left(x \right)}\right) = 2 \tan{\left(1 \right)}$$ More at x→1 from the right $$\lim_{x \to -\infty}\left(2 \tan{\left(x \right)}\right)$$ More at x→-oo