2. Упростите выражение: a) (c-2)(c+3)-(c-1)²; б) 3(a+c)²-6ac.

a) (c-2)(c+3)-(c-1)² = (c² + 3c - 2c - 6) - (c² - 2c + 1) = c² + c - 6 - c² + 2c - 1 = 3c - 7
б) 3(a+c)²-6ac = 3(a² + 2ac + c²) - 6ac = 3a² + 6ac + 3c² - 6ac = 3a² + 3c²