Use the determinant b(squared) - 4ac

if it is>0 then 2 real solutions

if it =0 then 1 real solution

if it<0 2 imaginary solutions

a)(-12)(squared) - 4(4)(9) = 0 so: 1 real

b)5(squared) - 4(2)(-1) = 33 so: 2 real

c)(-2)(squared) - 4(1)(3) =-8 so: 2 imaginary