Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

If $α$ and $β$ be the roots of ax2 + bx + c = 0 then $\underset{x→α}{\lim}(1+ax^2+bx+c)^{1/(x-a)}$ is :

Options:

$a(α-β)$

$ln|a(α-β)|$

$e^{(α-β)}$

$e^{a(α-β)}$

Correct Answer:

$e^{a(α-β)}$

Explanation:

$ax^2+ bx + c = 0, α, β$ are the roots   $⇒ax^2+bx+c≡a(x-α)(x-β)$

$\underset{x→α}{\lim}(1+a(x-α)(x-β))\frac{1}{x-α}$

$=\underset{(x→α)→0}{\lim}[1+a(x-α)(x-β)]\frac{a(x-β)}{a(x-β)(x-α)}=\underset{x→α}{\lim}e^{a(x-β)}=e^{a(α-β)}$