Вправи: 513

513. Виконайте множення:

1) (2 – 3)(3 + 1) = 23 + 2 – (3)² – 3 = 23 + 2 – 3 – 3 = 3 – 1;

2) (2 + 5)(22 – 5) = 2(2)² – 2 • 5 + 22 • 5 – (5)² = 2 • 2 – 10 + 210 – 5 = 10 – 1;

3) (a + b)(a – b) = a² – (b)² = a² – b;

4) (b – c)(b + c) = (b)² – (c)² = b – c;

5) (4 + 3)(4 – 3) = 4² – (3)² = 16 – 3 = 13;

6) (y – 7)(y + 7) = y² – (7)² = y² – 7;

7) (42 – 23)(23 + 42) = (42)² – (23) = 16 • 2 – 4 • 3 = 32 – 12 = 20;

8) (m + n)² = m² + 2mn + (n)² = m² + 2mn + n;

9) (a – b)² = (a)² – 2a • b + (b)² = a – 2ab + b;

10) (2 – 33)² = 2² – 2 • 33 + (33)² = 4 – 63 + 9 • 3 = 4 – 63 + 27 = 31 – 63.