$$(x+2y)(x-2y)+(9 { x }^{ 2 } +4 { y }^{ 2 } )+5 { y }^{ 2 }$$
Evaluate
$5\left(2x^{2}+y^{2}\right)$
Solution Steps
Consider $\left(x+2y\right)\left(x-2y\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.
Consider $\left(x+2y\right)\left(x-2y\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$.
