Hi,
Use the rational root theorem
IF f(x)=x^2+2x+1 = 0 Green
(x+1)(x+1)=0 |x = -1 is the single rational solution
IF f(x)=x^2-2x+5 = 0 Blue
(x-1)^2 + 4 =0 Completing the square
|x = 1 ± 2i NO rational roots
IF f(x)=x^2+4x-5 = 0 Purple
(x+5)(x-1)= 0
(x+5)= 0
x = -5
(x-1)= 0
x = 1
x = -5 and x = 1 are the rational solutions