The Graphs of General Polynomial Functions
Compared with the graph of the following also hold true.
- The graph of is reflected across the x-axis.
- The graph of is translated (shifted) k units up if k>0 and units down if k<0.
- The graph of is translated (shifted) h units to the right if h>0 and units to the left if h<0.
- The graph of shows a combination of these translations.
Examples
Graph each polynomial function. Determine the largest open intervals of the domain over which each function is increasing or decreasing.
Solutions
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The graph will be the same shape as that of but translated 2 units down. This function is increasing on its entire domain .
In , the function has a graph with the same shape as , but since , it is translated 1 unit to the left. This function is decreasing on ( ] and increasing on [).-
The negative sign in -2 causes the graph of the function to be reflected across the x-axis when compared with the graph of . Because , the graph is stretched vertically when compared to the graph of . It is also translated 1 unit right and 3 units up. This function is increasing on its entire domain .Domain & Range of Polynomial Functions
Unless otherwise restricted, the domain of a polynomial function is the set of all real numbers. Polynomial functions are smooth, continuous curves on the interval . The range of a polynomial function of odd degree is also the set of all real numbers.