Simplify :

$\Big(\dfrac{x^a}{x^{-b}}\Big)^{a^2 - ab + b^2} \times \Big(\dfrac{x^b}{x^{-c}}\Big)^{b^2 - bc + c^2} \times \Big(\dfrac{x^c}{x^{-a}}\Big)^{c^2 - ca + a^2}$

$\dfrac{a^{-1}}{a^{-1} + b^{-1}}$ is equal to :

1. $\dfrac{b}{a + b}$

2. $\dfrac{a + b}{a}$

3. $\dfrac{a}{a + b}$

4. a(a + b)

$\dfrac{3x}{y^{-1}} + \dfrac{2y}{x^{-1}}$ 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. $\dfrac{1}{2}$