Which is the value of the sum x1+x2+x3, if x1, x2, x3 are the solutions of the equation x^3-3x^2+2x=0?

The equation x^3
-3x^2 +2x =0

is a third power polynomial . Then it has 3 roots:

x1, x2, and x3

In the standard form of third power
polynomial:

ax^3+bx^2+cx+d=0

Viete' relation states
that:

x1+x2+x3= -b/a

Then in our equation:

a= 1

b=-3

c=2

d=0

Then x1+x2+x3= -b/a= 3