Without graphing, determine whether each quadratic equation has no real roots, one real root, or two real roots. If a root is real, indicate whether it is rational or irrational.
a. y = 2x2 - 5x - 3
b. y = x2 + 4x - 1
c. y = 3x2 - 3x + 4
d. y = 9x2 - 12x + 4