RESOLVER:
[tex]\left(20mn+5\right)\left(-5+20mn\right)[/tex]
[tex]\left(20mn+5\right)\left(-5+20mn\right)=\left(20mn\right)^2-5^2[/tex]
[tex]=\left(20mn\right)^2-5^2[/tex]
Simplificamos esta expresión [tex]\left(20mn\right)^2-5^2:400m^2n^2-25[/tex]
[tex]\boxed{=400m^2n^2-25}[/tex]
[tex]BUENA\:\:SUERTE[/tex]
