4х+х+2х=1246
7х=1246
х=1246/7
х=178 км
2*178=356 км во второй
Х.....-2.....-1.....0......1......2......3......4
у......2......1.....0.....-1.....-2.....-3.....-4
Xy/(x-y)(1/x+1/y)-(x+y)/(x-y)=
1. 1/x+1/y=(x+y)/(xy)
2. xy/(x-y)*(x+y)/(xy)=(x+y)/(x-y)
3. (x+y)/(x-y)-(x+y)/(x-y)=0
Ответ: 0
-0,6(1,6b-5) - (2.9b-8) - 4(4-1.5b)= - 0.96b+3-2.9b+8-16+6b=2.14b-5
если b= - 9/13, то
- 2,14*9/13-5= - 2 7/50*9/13 - 5= - (107*9) / (50*13) - 5= - 1 313/650 - 5= - 6 313/650