how do you graph x square minus four x plus five equals zero
You don't graph an equation, you graph a function. In this case, you would probably be asked to make a graph of x^2 -4x +5 vs. x (which I assume you know how to do) and look for which values of x the curve crosses the x axis (where y = 0). In this case, it never does cross that axis. The lowest point of the curve is above the x axis. That is because
x^2 -4x + 5 = (x-2)^2 + 1
cannot be less than 1, for any x.