Consider, for example one of the easiest equations to graph:
y = x or f(x) = x in functional notation.
When you plug values into the independent variable, x, the dependent variable, y, has the same value. When x is 1, y is 1. When x is 2, y is 2. When x is -4, y is -4. Plotting the points on a coordinate plane result in a line that goes through the origin, rising to the right as much as it runs.
So if y = x is the parent equation, compare the following to it.
y = x +5
y = x – 2
y = x + 3
y = x – 1