Lec 38 - Graphs of Polynomials: Multiplicities | Summary and Q&A

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August 19, 2021
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IIT Madras - B.S. Degree Programme
Lec 38 - Graphs of Polynomials: Multiplicities

TL;DR

Learn how to identify the zeros of polynomial functions by analyzing their graphs and understand the behavior of the graph based on the multiplicities of the zeros.

Key Insights

• 🔍 Graphing a polynomial function:
• The knowledge of x-intercepts helps in understanding the shape of the polynomial graph and whether it goes up or down.
• To find the x-intercepts of a polynomial, one can plot a table of values and identify the points where the function equals zero.
• Long division can be used to factorize the given polynomial and find all the x-intercepts.
• A cubic polynomial can have at most three roots.
• Plotting the function along with the table of values helps visualize the curve of the polynomial.
• Understanding the behavior of the graph around the x-intercepts is crucial and related to the multiplicities of the factors.
• Polynomial factors with odd multiplicities will result in graphs crossing the x-axis, while those with even multiplicities will bounce off.
• The shape of the graph changes with the degree of the polynomial, with even-degree polynomials appearing flatter near the x-axis and odd-degree polynomials being steeper.
• Identifying the multiplicities of the zeros allows for a better understanding of the graph and the polynomial function.

Transcript

So, now, so far, we have mastered two skills; given a graph of a polynomial function, I know whether the given function is I can identify whether the given function is a polynomial function or not, ok. The second thing thatwe have seen isfrom algebraic expression of polynomial function whether it is in factored form or non-factored form, I have som... Read More

Q: How can we identify the x-intercepts of a polynomial function using its graph?

To find the x-intercepts, we can plot the function values at certain points and observe where the function crosses the x-axis. By doing this, we can determine the x-values that correspond to the zeros of the polynomial.

Q: What is the significance of the multiplicities of the zeros in a polynomial function?

The multiplicities of the zeros indicate how many times each zero is repeated in the factored form of the polynomial. This information helps us understand the behavior of the graph near the zeros. Odd multiplicities result in the graph crossing the x-axis, while even multiplicities cause the graph to bounce off the x-axis.

Q: How does the graph of a polynomial function behave near its zeros?

If a zero has an odd multiplicity, the graph of the polynomial will cross the x-axis at that point. On the other hand, if a zero has an even multiplicity, the graph will bounce off the x-axis at that point.

Q: How can we determine the factored form of a polynomial function from its graph?

By identifying the x-intercepts (zeros) of the function using its graph, we can use the knowledge of these zeros to write the polynomial in factored form. This involves applying long division to the polynomial and factoring out the corresponding factors for each zero.

Summary & Key Takeaways

• By analyzing the graph of a polynomial function, we can identify its zeros and determine whether it is in factored form or non-factored form.

• To find the x-intercepts (zeros) of a polynomial function, one method is to plot the function values at certain points and observe where the function crosses the x-axis.

• The behavior of the graph near the zeros can be determined by looking at the factors of the polynomial and their multiplicities. Odd-degree factors result in the graph crossing the x-axis, while even-degree factors lead to the graph bouncing off the x-axis.