$\tan ^{-1} 3+\tan ^{-1} \lambda=\tan ^{-1} \frac{3+\lambda}{1-3 \lambda}$ is valid for which values of $\lambda$ ?
Answer & explanation
Correct answer: option 3
so $\tan ^{-1} 3+\tan ^{-1} \lambda=\tan ^{-1} \frac{3+\lambda}{1-3 \lambda}$
so $3 \lambda<1$
so $\lambda<1 / 3$