$\dfrac{3x}{y^{-1}} + \dfrac{2y}{x^{-1}}$ is equal to :

1. 6xy

2. 3x² + 2y²

3. 5xy

4. $\dfrac{6}{xy}$

$\Big(8^{-\dfrac{4}{3}} ÷ 2^{-2}\Big)$ is equal to :

1. $\dfrac{1}{4}$

2. $-\dfrac{1}{4}$

3. $-\dfrac{1}{2}$

4. $\dfrac{1}{2}$

If 3^{x + 1} = 9^{x - 2}, the value of x is :

1. -5

2. 5

3. 0

4. 3

If $\sqrt{\dfrac{a}{b}} = \Big(\dfrac{b}{a}\Big)^{1 - 2x}$, the value of x is :

1. $\dfrac{3}{4}$

2. $\dfrac{3}{5}$

3. $-\dfrac{3}{4}$

4. $-\dfrac{3}{5}$