Question

Write down the series whose $r^{th}term$ s ${3.2}^{r+1}?$

• A.
  $0,2,4,...$
• B.
  $10,20,30,...$
• C.
  $5,10,15,...$
• D.
  $12,24,48,...$

Answer 1

The correct option is D

$12,24,48,...$
$a_r={3.2}^{r+1}{a}_1={3.2}^{1+1}=12a_2={3.2}^{2+1}=24a_3={3.2}^{3+1}=4812,24,48,....\frac{a_2}{a_1}=\frac{24}{12}=2,\frac{a_3}{a_2}=\frac{48}{24}=2\text{Thus, it is a G.P.}$
Hence, option d is correct