Question

x^2-4x+c=0
two real numbers
one real number
two imaginary numbers

Answer 1

use quadratic formula but leave the c in there and post what you get

Answer 2

instead of c being a number when you usually do it leave it as C

Answer 3

or you can sub in a random value for c

Answer 4

\[\Large\rm x=\frac{-b\pm\sqrt{\color{orangered}{b^2-4ac}}}{2a}\]Yah your quadratic formula is the way to go :)
Number of solutions is determined by this orange part, we call it the discriminant.

Answer 5

looks good so far.