Question

Write down the first five terms of the geometric progression which has first term 1 and common ratio 4.

• A. 1, 4, 16, 64, 244
• B. 1, 4, 24, 64, 256
• C. 1, 4, 16, 32, 256
• D. 1, 4, 16, 64, 256

Answer 1

The correct option is D 1, 4, 16, 64, 256

Let a and d be the first term and common ratio of the GP respectively.
Given a=1 and d=4.
Now, $a_n=a{r}^{n-1}$
$\therefore a_1=a=1$
$a_2=ar=1\times 4=4$
$a_3=a{r}^2=1\times (4{)}^2=16$
$a_4=a{r}^3=1\times (4{)}^3=64$
$a_5=a{r}^4=1\times (4{)}^4=256$