(3у)*(3+у) = 9у + 3у^2
(3v-1)*(3v+1) = 9v^2 - 1
(5v+6)*(5v-6) = 25v^2 - 36
(a+2v)*(a-2v) = a^2 - 4v^2
(5c+2a)*(5c-2c) = 25c^2 - 4a^2
(4v+1)*(1-4v) = -16v^2 - 4v + 4v - 1 = -16v^2 - 1
(3у)*(3+у) = 9у + 3у^2
(3v-1)*(3v+1) = 9v^2 - 1
(5v+6)*(5v-6) = 25v^2 - 36
(a+2v)*(a-2v) = a^2 - 4v^2
(5c+2a)*(5c-2c) = 25c^2 - 4a^2
(4v+1)*(1-4v) = -16v^2 - 4v + 4v - 1 = -16v^2 - 1