 Figure 1: Decreasing function 

A decreasing function is a
function
whose values become smaller as the argument of the function increases.^{[1]} The graph of
a decreasing function descends from upper left to lower right. Figure 1 shows the graph
of the function
A function can also be decreasing on a subset of the domain of the function. This is
usually called increasing on an interval or decreasing on an interval. Figure 2
shows the graph of y = x^{2}+3. This function is increasing on the
interval from negative infinity to 0. This function is also decreasing on the interval
from 0 to infinity.

 Figure 2: Increasing and decreasing on an interval. 
