krugly1981 ( b - 3c)(b + 3c) - ( 2b + c)(2b - c) = b^2 - 9c^2 - ( 4b^2 - c^2) =
= b^2 - 9c^2 - 4b^2 + c^2 = - 3b^2 - 8c^2

ВластелинВселенной =(b2+3bc-3bc-9c2)-(2bc-c2+4b2-2bc)=(b2-9c2)-4b2-c2)=b2-9c2-4b2+c2=-3b2-8c2