17 х - х + 5 х =170 +19
21 х = 189
х = 189 : 21
х = 9
Проверка
17 х 9 - 9 + 5 х 9 - 19 = 170
170 = 170
17 х 9 - 9 +5 х 9 - 19 = 153 - 9 +45 - 19 = 144+45 = 19 = 189 - 19 = 170
Sqrt20 = 2sqrt5
sqrt320 = 8sqrt5
2sqrt5*8sqrt5 = 16*5 = 80
(c-8d+6d)*(-1.2)=-1,2с+9,6d-7,2d=-1,2с+2,4d=-1,2(c-2d)
BF=X AF=x+15 (x+15) x= 4*25 D= 625 x1=5 x2=-20 AF= 5+15 = 20
25-5=20******************