Visualisation of Identity 2

Q. Find the values of a and b if
$\frac{7+\sqrt{5}}{7-\sqrt{5}}-\frac{7-\sqrt{5}}{7+\sqrt{5}}=a+\frac{7}{11}\sqrt{5}b$

Q. The value of $(\sqrt{15}+\sqrt{10})(\sqrt{15}-\sqrt{10})$ is equal to

1. 2
2. 5
3. 6
4. 7

Q. The value of $(4+\sqrt{6})(4-\sqrt{6})$ is equal to

1. $2$
2. $6$
3. $8$
4. $10$

Q. Evaluate ($\sqrt{6}$+$\sqrt{3}$) ($\sqrt{6}$-$\sqrt{3}$)

Q. The value of $(\sqrt{15}+\sqrt{10})(\sqrt{15}-\sqrt{10})$ is equal to _____.