Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

The relationship between a and b making f(x) continuous at x=3, were $f(x) = \begin{cases} ax + 1, & x \le 3 \\ bx + 3, & x > 3 \end{cases}$ is :

Options:

3a - 3b = 2

a - b = 4

a + b + 4 = 0

a + b = 0

Correct Answer:

3a - 3b = 2

Explanation:

The correct answer is Option (1) → $3a - 3b = 2$

$\lim\limits_{x→3^-}(ax+1)=f(3)=3a+1$

$\lim\limits_{x→3^+}(bx+3)=3b+3$

$⇒3a+1=3b+3$

so $3a-3b=2$