Упростите: 12^2-(х+7)^2-(5-х)(19+х)

Question

Упростите: 12^2-(х+7)^2-(5-х)(19+х)

Answer 1

12^2-(х+7)^2-(5-х)(19+х)=

=12х^2-х^2-14х-49-95+14х+х^2=12х^2-144=

=12(х^2-12)