Question

Докажите, что при любых целых m и n делится на 8 значение выражения:
(2m+n-3)(2m+n+1)-(2m-n+3)(2m-n-1)

Answer 1

4m^2+2mn+2m+2mn+n^2+n-6m-3n-3-(4m^2-2mn-2m-2mn+n^2+n+6m-3n-3)=4m^2+2mn+2m+2mn+n^2+n-6m-3n-3-4m^2+2mn+2m+2mn-n^2-n-6m+3n+3=8mn-8m