The common ratio of the G.P. $\dfrac{1}{a^3x^3},\ ax,\ a^5x^5,\ \dots$ is :

1. $\dfrac{1}{a^2x^2}$

2. $\dfrac{1}{a^4x^4}$

3. a²x²

4. a⁴x⁴

The common ratio of the G.P. 0.15, 0.015, 0.0015, …… is :

1. 0.1

2. 0.01

3. 1

4. 0.001

The nth term of the G.P. x³, x⁵, x⁷, …….. is :

1. x^{(2n - 1)}

2. x^{(2n + 3)}

3. x^{(2n + 1)}

4. x^{3n + 2}

The 10th term of the G.P. 1, −a, a², −a³, …….. is :

1. a⁹

2. −a¹⁰

3. −a¹¹

4. −a⁹