If x = 5 + $2\sqrt{6}$, then $x^2 + \dfrac{1}{x^2}$ =

1. 98

2. 142

3. 49

4. 138

Two rational numbers between $-\dfrac{3}{7} \text{ and } -\dfrac{1}{7}$ is :

1. $\dfrac{4}{14}, \dfrac{3}{14}$

2. $-\dfrac{4}{14}, \dfrac{3}{14}$

3. $\dfrac{4}{14}, -\dfrac{3}{14}$

4. $-\dfrac{4}{14}, -\dfrac{3}{14}$

The mixed surd for $\sqrt[3]{432}$ is :

1. $2\sqrt[3]{6}$

2. $6\sqrt[3]{2}$

3. $3\sqrt[3]{6}$

4. $6\sqrt[3]{3}$

What is the pure surd for $5\sqrt[3]{2}$ ?

1. $\sqrt[3]{125}$

2. $\sqrt[3]{150}$

3. $\sqrt[3]{250}$

4. $\sqrt[3]{1000}$