Вправи: 1347

1347. Обчисли.

а) 24² – 14² = (24 – 14)(24 + 14) = 10 • 38 = 380;

б) 62² – 38² = (62 – 38)(62 + 38) = 24 • 100 = 2400;

в) 98² – 97² = (98 – 97)(98 + 97) = 1 • 195 = 195;

г) 52,5² – 48,5² = (52,5 – 48,5)(52,5 + 48,5) = 4 • 101 = 404;

ґ) 14,3² – 4,3² = (14,3 – 4,3)(14,3 + 4,3) = 10 • 18,6 = 186;

д) 5,9² – 5,1² = (5,9 – 5,1)(5,9 + 5,1) = 0,8 • 11 = 8,8;

е) (1734)² – (1634)² = (1734 – 1634)(1734 + 1634) = 1 • 3364 = 33 + 124 = 33 + 1,5 = 34,5.

є) (723)² – (213)² = (723 – 213)(723 + 213) = 513 • 20 = 163 • 10 = 1603 = 5313.