$r^2 - 5r + 6 = 0$ (roots: $2, 3$)

$r^2 + 4r + 4 = 0$ (repeated root: $-2$)

$r^2 + 2r - 8 = 0$ (roots: $2, -4$)

$r^2 - 4r + 4 = 0$ (repeated root: $2$)