How do you graph #x^2 - 4y + 16 = 0#?
Calculate the desired number of data points, and put them on an appropriate graph paper.
ANY graphing or plotting must start with a table of values of the independent variable and the evaluated expression. With those values you may plot them on graph paper manually, or use a computer plotting program.
Sometimes, we just want a rough sketch, in which case recognizing the general forms of common equations such as lines, parabolas, and cubics is helpful. For this case, I am assuming that you meant to write