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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 69

Find a polynomial function f of least degree having the graph shown. (Hint: See the NOTE following Example 4.)

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Step 1: Identify the roots of the polynomial from the graph. The graph crosses the x-axis at x = -3 and x = 3, so these are roots of the polynomial. Since the graph touches the x-axis and turns around at these points, the roots have even multiplicity (likely multiplicity 2).
Step 2: Note the local maximum at (0, 16). This point gives us the y-intercept of the polynomial, so when x = 0, f(x) = 16.
Step 3: Write the general form of the polynomial using the roots and their multiplicities. Since the roots are at x = -3 and x = 3 with multiplicity 2, the polynomial can be expressed as \(f(x) = a(x + 3)^2 (x - 3)^2\) where \(a\) is a constant to be determined.
Step 4: Use the y-intercept to find the value of \(a\). Substitute x = 0 and f(0) = 16 into the polynomial: \(16 = a(0 + 3)^2 (0 - 3)^2\). Simplify and solve for \(a\).
Step 5: Write the final polynomial function with the determined value of \(a\). This polynomial will be of least degree and match the graph shown.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Polynomial Function and Degree

A polynomial function is an expression consisting of variables and coefficients combined using addition, subtraction, and multiplication, with non-negative integer exponents. The degree of the polynomial is the highest exponent of the variable, which determines the general shape and number of turning points of the graph.
추천 영상:
06:04
Introduction to Polynomial Functions

Zeros and Their Multiplicities

Zeros of a polynomial are the x-values where the function equals zero. The multiplicity of a zero affects the graph's behavior at that point: an odd multiplicity causes the graph to cross the x-axis, while an even multiplicity causes it to touch and turn around without crossing.
추천 영상:
03:42
Finding Zeros & Their Multiplicity

Local Maximum and Critical Points

A local maximum is a point where the function changes from increasing to decreasing, creating a peak on the graph. Identifying local maxima helps determine the polynomial's turning points, which relate to the degree and shape of the polynomial function.
추천 영상:
02:44
Maximum Turning Points of a Polynomial Function