Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

If the function $f(x)=\left\{\begin{matrix}\frac{x^3-(k+4)x+2k}{x-3},&x≠3\\8,&x=3\end{matrix}\right.$ is continuous at x = 3, then k is:

Options:

3

-3

-15

15

Correct Answer:

15

Explanation:

$\underset{x→3}{\lim}\frac{x^3-(k+4)x+2k}{x-3}=\underset{x→3}{\lim}\frac{3x^2-(k+4)}{1}=23-k$

⇒ 23 - k = 8

⇒ k = 15