Question Number 55072 by peter frank last updated on 17/Feb/19
Commented by mr W last updated on 17/Feb/19
$$\left({ax}+{by}\right)\left({bx}−{ay}\right)=\mathrm{0} \\ $$$${abx}^{\mathrm{2}} −\left({a}^{\mathrm{2}} −{b}^{\mathrm{2}} \right){xy}−{aby}^{\mathrm{2}} =\mathrm{0} \\ $$$$\Rightarrow{x}^{\mathrm{2}} −{y}^{\mathrm{2}} −\frac{{a}^{\mathrm{2}} −{b}^{\mathrm{2}} }{{ab}}{xy}=\mathrm{0} \\ $$