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Precalculus Lesson 2.2. Polynomial Functions of Higher Degree. Characteristics of Graphs of Polynomials. Polynomial functions are continuous . This means that the graphs of polynomial functions have no breaks, holes, or gaps .
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PrecalculusLesson 2.2 Polynomial Functions of Higher Degree
Characteristics of Graphs of Polynomials • Polynomial functions are continuous. This means that the graphs of polynomial functions have no breaks, holes, or gaps. • The graphs of polynomial functions have only nice smooth turns and bends. There are no sharp turns, as in the graph of y = |x|.
f(x) = xn Here n is even. Note how the graph flattens at the origin as n increases.
f(x) = xnHere n is odd. Note how the graph flattens at the origin as n increases.
Using the Leading Coefficient Test Describe the right-hand and left-hand behavior of the graph of each function. Ask yourself 2 questions: • Is a positive or negative? • Is the exponent on the leading variable even or odd? • f(x) = -x4 + 7x3 – 14x – 9 b) g(x) = 5x5 + 2x3 – 14x2 + 6
Zeros of Polynomial Functions For a polynomial function f of the degree n, the following statements are true: • The function f has at most n zeros. • The graph of f has at most n-1 relative maxima/minima. (Has at most n-1 turns)
Zeros of a Polynomial Function When f is a polynomial function and a is a real number: 1. x = a is a zero of f. 2. x = a is a solution of the equation f(x) = 0. 3. (x – a) is a factor of f(x). 4. (a, 0) is an x-intercept of the graph of f. These statements are all equivalent!
Find all the real zeros. f(x) = x3 – x2 – x + 1
The Graph of f(x) = x3 – x2 – x + 1. Note that in the above example, 1 is a repeated zero. In general, a factor of (x – a)k, k > 1, yields a repeated zero x = a of multiplicity k. If k is odd, the graph crosses the x-axis at x = a. If k is even, the graph only touches the x-axis at x = a.
Some information you need to sketch the graph of f(x) = x3 – 2x2 • At most, how many real zeros does this function have? • At most, how many turns does this graph have? • Factor f(x) • What are the x-intercepts based on the factoring? • What do the multiplicity rules tell you about your x-intercepts? • What does the leading coefficient test tell you about the end behavior of your graph?
Sketching the Graph of a Polynomial Function Apply the leading coefficient test to determine the end behavior of the graph. Determine the possible number of x-intercepts and turns. Find the real zeros of the polynomial. Plot a few additional points. (Make a table) Draw the graph.