Question

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

• A. $4^3$
• B. $4^4$
• C. $4^5$
• D. $4^6$

Answer 1

The correct option is C $4^5$

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

$a_3=4⟹a{r}^2=4$

Productof first five terms = $a_1.a_2.a_3.a_4.a_5$

$=a\left(ar\right)\left(a{r}^2\right)\left(a{r}^3\right)\left(a{r}^4\right)=a^5{r}^{10}=(a{r}^2{)}^5=4^5$