Q101 / 160 · AP EAMCET 2023 (18 May Shift 2) · Mathematics
Let [.] denote the greatest integer function.
Assertion (A) : $\lim _{x \rightarrow \infty} \frac{[x]}{x}=1$
Reason $(R)$ : $f(x)=x-1, g(x)=[x], h(x)=x$ and $\lim _{x \rightarrow \infty} \frac{f[x]}{x}=\lim _{x \rightarrow \infty} \frac{h(x)}{x}=1$
- Correct answerAA is true, $\mathrm{R}$ is true: $\mathrm{R}$ is correct explanation of $\mathrm{A}$
- BA, R are true; R is not the correct explanation of $A$
- C$\mathrm{A}$ is true, $\mathrm{R}$ is false
- DA is false, R is true
Solution
A: $\lim _{x \rightarrow \infty} \frac{[x]}{x}=\lim _{x \rightarrow \infty} \frac{x-\{x\}}{x}$
$$
\begin{array}{ll}
=\lim _{x \rightarrow \infty} 1-\frac{\{x\}}{x}=1-0 & \{\because 0 < \{x\} < 1\} \\
= & \lim _{x \rightarrow \infty} \frac{[x]}{x}=1
\end{array}
$$
$\therefore \quad$ Assertion is true
B: $\lim _{x \rightarrow \infty} \frac{f[x]}{x}=\lim _{x \rightarrow \infty} \frac{[x]-1}{x}=\lim _{x \rightarrow \infty} \frac{[x]}{x}=1$
Reason is true.
Hence, the correct answer is option: 'A'.