Вправи: 777

777. Спростіть вираз:

1) (7 – 12)(7 + 33) = 7 + 321 – 12 • 7 – 336 = 7 + 321 – 221 – 3 • 6 = 21 – 11;

2) (3 – 11)(33 + 1) = 3311 + 3 – 11113 – 11 = 311 + 3 – 113 – 11 = 211 – 103;

3) 42(2 – 78) – 72 = 82– 2816 – 72 = 2 – 28 • 4 = 2 – 112;

4) (5 + 1)(2 – 5) – 5 = 25 – 5 + 2 – 5 – 5 = –3;

5) (3 – 7)(4 – 3) – 113 = 43 – 3 – 28 + 73 – 113 = –31;

6) (2 + 3)(1 – 3) + 1 = 2 – 23 + 3 – 3 + 1 = –3.