Find the $17^{\text {th }}$ and nth terms of the GP $2,2 \sqrt{2}, 4,8 \sqrt{2} \ldots .$
Given GP is $2,2 \sqrt{2}, 4,8 \sqrt{2} \ldots \ldots$
The given GP is of the form, $a, a r, a r^{2}, a r^{3} \ldots .$
Where $r$ is the common ratio.
First term in the given GP, $a_{1}=a=2$
Second term in GP, $a_{2}=2 \sqrt{2}$
Now, the common ratio, $\mathrm{r}=\frac{\mathrm{a}_{2}}{\mathrm{a}_{1}}$
$r=\frac{2 \sqrt{2}}{2}=\sqrt{2}$
Now, $\mathrm{n}^{\text {th }}$ term of GP is, $\mathrm{a}_{\mathrm{n}}=\mathrm{ar}^{\mathrm{n}-1}$
So, the $17^{\text {th }}$ term in the GP,
$a_{17}=a r^{16}$
$=2 \times(\sqrt{2})^{16}$
$=512$
$\mathrm{n}^{\text {th }}$ term in the GP,
$a_{n}=a r^{n-1}$
$=2(\sqrt{2})^{n-1}$
$=(\sqrt{2})^{n+1}$
Hence, $17^{\text {th }}$ term $=512$ and $\mathrm{n}^{\text {th }}$ term $=(\sqrt{2})^{\mathrm{n}+1}$