Consider $\left(3+2\sqrt{5}\right)\left(3-2\sqrt{5}\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.
Consider $\left(3+2\sqrt{5}\right)\left(3-2\sqrt{5}\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.
Divide $\frac{9\sqrt{5}}{11}-\sqrt{5}a-\frac{19}{11}$ by $-\frac{19}{11}$ by multiplying $\frac{9\sqrt{5}}{11}-\sqrt{5}a-\frac{19}{11}$ by the reciprocal of $-\frac{19}{11}$.