...=a-b+b-c+c-a=0
...=x^2-7xy-5+4xy+3xy-x^2=-5
...=0.5a^4
...=-3b^20*b^3/27=-b^23/9
{x-2y=4
{x*y=6
{x=4+2y
{(4+2y)y=6
{x=4+2y
{4y+2y^2-6=0 |:2
{x=4+2y
{y^2+2y-3=0
{x=4+2y
{y1=-3; y=1
{x1=-2; x2=6
{y1=-3; y2=1
ответ: (-2; -3) v (6; 1)
4-186
5-45
6-4.8
7-150
8-0.25
9-4
10-0.1