Question
If $P(n)$ is the statement " $2^n \geq 3 n$ " and if $P(r)$ is true, prove that $P(r+1)$ is true.

Answer

$P(n): 2^n \geq 3 n$
Given that $P(r)$ is true
$\Rightarrow 2^r \geq 3 r$
Multiplying both sides by $2$ ,
$2.2^r \geq 2.3 r$
$2^{r+1} \geq 6 r$
$2^{r+1} \geq 3 r+3 r$
$\left.2^{r+1} \geq 3+3 r, \text { [Since } 3 r \geq 3 \Rightarrow 3 r+3 r \geq 3+3 r\right]$
$2^{r+1} \geq 3 r(r+1)$
$\Rightarrow P(r+1) \text { is true. }$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free