2. Упростите: 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