The sum of n terms of a G.P. with first term a and common ratio r, when r > 1, is :

1. $\dfrac{ar^n-1}{r-1}$

2. $\dfrac{1-ar^n}{1-r}$

3. $\dfrac{a(r^n-1)}{r-1}$

4. $\dfrac{a(1-r^n)}{1-r}$

The sum of n terms of a G.P. with first term a and common ratio r, when r < 1, is :

1. $\dfrac{ar^n-1}{r-1}$

2. $\dfrac{1-ar^n}{1-r}$

3. $\dfrac{a(r^n-1)}{r-1}$

4. $\dfrac{a(1-r^n)}{1-r}$

The 12th term of the G.P. 2, 4, 8, 16, ……. is :

1. 1024

2. 2048

3. 4096

4. 8192

Which term of the G.P. $\sqrt{3}, 3\sqrt{3}, 9\sqrt{3}, \dots$ is $729\sqrt{3}$ ?

1. 7th

2. 6th

3. 9th

4. 8th