Consider $\left(11+3\sqrt{11}\right)\left(11-3\sqrt{11}\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.
Consider $\left(11-3\sqrt{11}\right)\left(11+3\sqrt{11}\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.