The roots of a quadratic equation ax^2+bx+c=0 are 1+i√5 and 1−i√5 . Find possible values of a, b and c.

y = a(x-(1+i√5))(x-(1-i√5))

= a((x-1)-i√5)((x-1)+i√5)
= a((x-1)^2 - (i√5)^2)
= a(x^2-2x+1+5)
= a(x^2-2x+6)
b = -2a, c = 6a
a+b+c = 5a
a can be whatever you want.
Did you leave out something?