Can Functions Be Negative?

Function values can be positive or negative, and they can increase or decrease as the input increases.

Can function values ever be negative?

It definitely can, say f(x)=−1 for every possible x. The average of f in any interval is −1.

What happens when a function is negative?

To keep straight what this transformation does, remember that f (x) is the exact same thing as y. So, by putting a "minus" on everything, you're changing all the positive (above-axis) y-values to negative (below-axis) y-values, and vice versa. (Any points on the x-axis stay right where they are.