Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

For what value of $α$, the function $f$ defined by $f(x) = \left\{\begin{matrix}a(x^2-2x+1),& if\, x ≤0\\2x+1,& if\, x > 0\end{matrix}\right.$ is continuous at $x = 0$?

Options:

$α = 1$

$α = 2$

$α=-1$

$α = 0$

Correct Answer:

$α = 1$

Explanation:

The correct answer is Option (1) → $α = 1$

Given: The function is

$f(x) = \begin{cases} a(x^2 - 2x + 1), & \text{if } x \leq 0 \\ 2x + 1, & \text{if } x > 0 \end{cases}$

To ensure continuity at $x = 0$, we must have:

$\lim_{x \to 0^-} f(x) = \lim_{x \to 0^+} f(x) = f(0)$

Left-hand limit (LHL):

$\lim_{x \to 0^-} f(x) = a(0^2 - 2 \cdot 0 + 1) = a(1) = a$

Right-hand limit (RHL):

$\lim_{x \to 0^+} f(x) = 2 \cdot 0 + 1 = 1$

Also, $f(0) = a(0^2 - 2 \cdot 0 + 1) = a$

For continuity: $a = 1$