Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

Evaluate $\underset{x→2}{\lim}\frac{\sqrt{x^2+x-3}-\sqrt{x+1}}{x-2}$.

Options:

$\frac{1}{\sqrt{3}}$

$\sqrt{3}$

$\frac{2}{\sqrt{3}}$

$2\sqrt{3}$

Correct Answer:

$\frac{2}{\sqrt{3}}$

Explanation:

$\underset{x→2}{\lim}\frac{\sqrt{x^2+x-3}-\sqrt{x+1}}{x-2}=\frac{x^2-4}{(x-2)(\sqrt{x^2+x-3}-\sqrt{x+1})}$(Rationalise)

$\underset{x→2}{\lim}\frac{x+2}{(\sqrt{x^2+x-3}-\sqrt{x+1})}=\frac{4}{2\sqrt{3}}=\frac{2}{\sqrt{3}}$