Задачі і вправи для повторення » 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) (173/4)2 – (163/4)2 = (173/4 – 163/4)(173/4 + 163/4) = 1 • 336/4 = 33 + 12/4 = 33 + 1,5 = 34,5. є) (72/3)2 – (21/3)2 = (72/3 – 21/3)(72/3 + 21/3) = 51/3 • 20 = 16/3 • 10 = 160/3 = 531/3.