A function 
is said to be strictly increasing on an interval 
if 
for all 
,
where 
.
On the other hand, if 
for all 
, the function is said to be (nonstrictly) increasing.
Strictly Increasing Function
See also
Decreasing Function, Derivative, Nondecreasing Function, Nonincreasing Function, Strictly Decreasing FunctionExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Strictly Increasing Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/StrictlyIncreasingFunction.html