Пожалуйста помогите. вычислите с поддержкою формулы

Ответ:

Пошаговое объяснение:

2) 20-19 = (20-19)(20+19) = 139 = 39

4) 3,5-3,7 = (3,5-3,7)(3,5+3,7) = -0,27,2 = -1,44

6) (7/9)-(1/6)= (7/9-1/6)(7/9+1/6) = (14/18-3/18)(14/18+3/18) = 11/1817/18 = 187/324

8) (3/10)-(4/5) = (3/10)-(8/10) = (3/10-8/10)(3/10+8/10) = -5/1011/10 = -11/20

10) (2 1/7)-(2 1/7) = 0

12) (5 1/6)-(7 1/3) = (5 1/6)-(7 2/6) = (5 1/6-7 2/6)(5 1/6+7 2/6) = -2 1/612 3/6 = -13/625/2 = -325/12 = -27 1/12

14) 54-46 = (54-46)(54+46) = 8100 = 800

16) 328-172 = (328-172)(328+172) = 156500 = 78000

18) (7 5/9)-(4 4/9) = (7 5/9-4 4/9)(7 5/9+4 4/9) = 3 1/912 = 37 1/3