Вправи: 513

513. Спростіть вираз:

1) (8а – 3)(8a + 3) – (7а + 4)(8а – 4) = (8а)² – З² – (56а² – 28а + 32а – 16) = 64а² – 9 – 56а^{2 +} 28а – 32а + 16 = 8а² – 4а + 7;

2) 0,6m(2m – 1)(2m + 1) + 0,3(6 + 5m)(6 – 5m) = 0,6m(4m² – 1) +

+ 0,3(36 – 25m²) = 2,4m³ – 0,6m + 10,8 – 7,5m² = 2,4m³ – 7,5m² –

– 0,6m + 10,8;

3) (7 –2х)(7 + 2х) – (х – 8)(х + 8) – (4 – Зх)(5 + Зх) = 49 – 4х² – (х²

– 64) – (20 + 12x – 15х – 9x²) = 49 – 4x² – х² + 64 – 20 – 12х + 15х + 9х² = 4х² + Зх + 93;

4) –b²с(4b – с²)(4b + с²) + 16b⁴с = –b²с(16b² – с⁴) + 16b⁴с = –16b⁴с + b²с⁵ + 16b⁴с = b²с⁵.