Let $f: R→ R$ be defined as $f(x) = 100x + 1$, where $R$ is a set of real numbers, then
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → f is both one-one and onto
Given: $f : \mathbb{R} \rightarrow \mathbb{R}$ defined by $f(x) = 100x + 1$
1. Injective (One-one): Suppose $f(x_1) = f(x_2)$
$\Rightarrow 100x_1 + 1 = 100x_2 + 1 \Rightarrow x_1 = x_2$
So, $f$ is injective.
2. Surjective (Onto): Let $y \in \mathbb{R}$
Then $y = 100x + 1 \Rightarrow x = \frac{y - 1}{100} \in \mathbb{R}$
So, for every $y \in \mathbb{R}$, there exists $x \in \mathbb{R}$ such that $f(x) = y$
Hence, $f$ is surjective.