1. Non-Linear. This is a quadratic equation which produces a curved parabola.
2. Linear. The graph is a straight line. The equation is in the form y = mx+b where m = 0.04 and b = 1200. Replace x with s if you need to. Replace y with e if you need to.
3. Non-Linear. This is an exponential graph. It curves downward forever due to the base 0.2 being less than 1. It will slowly approach the asymptote y = 0
4. Linear. Similar to number 2 above. We can write the equation in the form y = mx+b where m = -42 is the sloe and b = 368 is the y intercept.