Ответ:
1. а) 3c(4c – 5) – (c – 8)(c – 7) = 12с²-15с-с²+7с+8с-56 = 11с²-56
б) (y – 5)^2 – (5 – y)(5 + y) = у²-10у+25-25+у² = 2у²-10у
в) 6(x – 2)^2 + 24x = 6х²-24х+24+24х = 6х²+24
2. а) 49x – x^3 = х(49-х²) = х(7-х)(7+х)
б) 7a^2 + 28ac + 28c^2 = 7(а²+4ас+4с²) = 7(а+2с)²
в) m^3 + 27 = m³+3³ = (m+3)(m³-3m+9)
3. (a^2 + 3a)^2 – (1 – a^2)(a + 1)(1 – a) – 5a(4a^2 + a) =
= а⁴+6а³+9а²-(1-а²)²-20а³-5а² = а⁴-14а³+4а²-1+2а²-а⁴ = -14а³+6а²-1