The teacher will be very surprised to see your correct solution 😉
2*x*(-1 + x)*(-2 + x) x*(-1 + x)*(-3 + x)*(-2 + x)
x - x*(-1 + x) + --------------------- - ---------------------------- = 0
3 3
-x*(x - 3)*(x - 2)*(x - 1)/3 + 2*x*(x - 2)*(x - 1)/3 - x*(x - 1) + x = 0