Increasing/Decreasing
A function 𝑓 is increasing on an interval when, for any two numbers 𝑎 and 𝑏 in the interval, 𝑎<𝑏 implies 𝑓𝑎<𝑓𝑏
In simpler terms, 𝑓 is increasing over an interval if no matter which two numbers you pick in the interval, the bigger 𝑥-value corresponds with the bigger 𝑦-value.
A function 𝑓 is decreasing on an interval when, for any two numbers 𝑎 and 𝑏 in the interval, 𝑎<𝑏 implies 𝑓𝑎>𝑓𝑏
In simpler terms, 𝑓 is decreasing over an interval if no matter which two numbers you pick in the interval, the bigger 𝑥-value corresponds with the smaller 𝑦-value.
We describe where a function is increasing/decreasing by giving an interval of 𝑥-values. NOT 𝑦-VALUES