Упростите выражение:(a+1)²+3(a-1)²-5(a+1)(a-1)=
(a +1)^2 + 3(a - 1)^2 - 5 (a + 1)(a - 1) = (a + 1)^2 + 3(a - 1)^2 - 5(a - 1)^2 = (a + 1)^2 - 2(a -1)^2 = a^2 + 2a + 1 - 2a^2 + 4a - 2 = -a^2 + 6a - 1