Упростите выражения: (b+c)(b-c)-b(b-2c); (a-c)(a+c)-c(3a-c); a(a+5b)-(a+b)(a-b);

(b + c)(b - c) - b(b - 2c) = (b^2 – c^2) – b^2 + 2bc = b^2 – c^2 – b^2 + 2bc = 2bc – c^2; (a - c)(a + c) - c(3a - c) = (a^2 – c^2) – 3ac + c^2 = a^2 – c^2 – 3ac + c^2 = a^2 – 3ac; a(a + 5b) - (a + b)(a - b) = a^2 - 5ab – (a^2 – b^2) = a^2 - 5ab – a^2 + b^2 = b^2 – 5ab;