1 . XY

• A. $xy=\frac{{\left(x+y\right)}^2}{2}-\frac{{\left(x-y\right)}^2}{2}$
• B. $xy=\frac{{\left(x-y\right)}^2}{2}-\frac{{\left(x+y\right)}^2}{2}$
• C. $xy={\left(x+y\right)}^2-{\left(x-y\right)}^2$
• D. $xy=\left(\frac{{\left(x+y\right)}^2}{2}\right)-\left(\frac{{\left(x-y\right)}^2}{2}\right)$

Answer: Option D

Explanation: