Вправи: 870

870. Спростіть вираз:

1) 18+82 = 16+82+ 2 = 42+ 2 •42+ (2)2 = (4+ 2)2 = |4 + 2| = 4 + 2;

2) 16+67 + 23-87 = 9+2 •37+ 7 + 16-87+7 = 32+ 2 •37+(7)2 + 42+2•47+(7)2 = (3+ 7)2 + (4- 7)2 = |3 + 7| + |4 – 7| = 3 + 7 + 4 – 7 = 7;

3) 26-617 – 66-1417 = 9-2 •317+17 – 49-2 •717+ 17 = 32- 2 •317+ (17)2 – 72- 2 •717+ (17)2 = (3- 17)2 – (7- 17)2 = |3 – 17| – |7 – 17| = –(3 – 17) – (7 – 17) = –3 + 17 – 7 + 17 = 217 – 10;

4) 46+1021 + 25-1021+21 = 25+1021+21 + 25-1021+21 = (5+ 21)2 + (5- 21)2 = |5 + 21| + |5 – 21| = 5 + 21) + 5 – 21 = 10.