Number of Roots of a Quadratic

$x^2 + 1 = 0$

$3x^2 - 2x - \frac{4}{3} = 0$

$-6x^2 + 5x - 8 = 0$

$-\frac{7}{8}x^2 + 2x + 4 = 0$

$9x^2 - 30x + 25 = 0$