Вправи: 758

758. Спростіть вираз:

1) (8x – 5)(8х + 5) + 25 = 64x² – 25 + 25 = 64х²;

2) 9m2 + (5 – 3m)(5 + 3m) = 9m² + 25 – 9m² = 25;

3) (2b – 3)(3 + 2b) – 4b² = (2b – 3)(2b + 3) – 4b² = 4b² – 9 – 4b² =

–9;

4) (4а + 7)(7 – 4а) – 49 = (7 + 4а)(7 – 4а) – 49 = 49 – 16а² – 49 =

–16а².