Special Products 2

= ${\left(A-B\right)}^{2}$ , where $A={x}^{2}$ and $B={y}^{2}$

= $A^2-2AB+B^2$

= ${\left({x}^{2}\right)}^{2}-2\left({x}^{2}\right)\left({y}^{2}\right)+{\left({y}^{2}\right)}^{2}$

= ${x}^{4}-2{x}^{2}{y}^{2}+{y}^{4}$