Initially, as xxx increases, yyy .
The slope of the graph is equal to
for all xxx between x=0x=0x, equals, 0 and x=3x=3x, equals, 3.
Starting at x=3x=3x, equals, 3, the function value yyy

as xxx increases.
The slope of the graph is equal to
for xxx between x=3x=3x, equals, 3 and x=5x=5x, equals, 5.
For xxx between x=0x=0x, equals, 0 and x=4x=4x, equals, 4, the function value yyy

000.
For xxx between x=4x=4x, equals, 4 and x=8x=8x, equals, 8, the function value yyy

000.