Question

The third term of a G.P. is 4. Find the product of its first five terms.

• A. $4^2$
• B. $5^3$
• C. $4^5$
• D. none of these

Answer 1

The correct option is C $4^5$

Let $a$ be the first term and $r$ the common ratio. Then,

$a_3=4$

$a{r}^2=4$

Therefore, product of first five terms = $a_1{a}_2{a}_3{a}_4{a}_5=a\left(ar\right)\left(a{r}^2\right)\left(a{r}^3\right)\left(a{r}^4\right)=a^5{r}^{10}$

$=(a{r}^2{)}^5=4^5$