# Strictly or Increasing function..

https://www.aplustopper.com/function-increasing-decreasing/

Hi , i was recently learning about strictly increasing and decreasing functions in school, and my teacher told that the graph that i attaches is increasing and not strictly increasing...But if we see the defination of strictly increasing , it says that slope should be always positive , and this satisfies that...so why is it not strictly increasing

• He is wrong. The definition is that $f(a)>f(b)$ for all $a>b$ for a function $f$ to be strictly increasing. Exactly that is the case here, so this function is strictly increasing – LegNaiB Jun 7 at 10:34

It could be that the bit in the middle is "supposed" to be horizontal, and it's just been drawn badly. If the bit in the middle is horizontal, then yes, it is an increasing function but not a strictly increasing one.

As it is, the graph you have shown us is strictly increasing, most definitely.