Найду корень уравнения: 5(x-3,8)=7x
5*(x - 19/5) = 7*x
5*(x-(19/5)) = 7*x
5*x+5*19/5) = 7*x
x = 19 / (-2)
x1 = -19/2
сумма
0 - 19/2
=
-19/2
произведение
1*-19/2
x1 = -9.5