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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 4, Problem 54

For each polynomial function, identify its graph from choices A–F.
ƒ(x)=(x2)2(x5) ƒ(x)=-(x-2)^2(x-5)
Six graphs labeled A to F show different polynomial curves with x-intercepts near 2 and 5 for matching a given function.

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Start by identifying the degree of the polynomial function ƒ(x) = -(x-2)^2(x-5). Since (x-2) is squared and (x-5) is to the first power, the degree is 2 + 1 = 3, which means the polynomial is cubic.
Determine the leading term by multiplying the highest degree terms from each factor: from (x-2)^2, the highest term is x^2, and from (x-5), it is x. Multiplying these gives x^3, and considering the negative sign, the leading term is -x^3.
Analyze the end behavior of the graph using the leading term -x^3: as x approaches positive infinity, ƒ(x) approaches negative infinity; as x approaches negative infinity, ƒ(x) approaches positive infinity.
Identify the zeros of the function from the factors: x = 2 (with multiplicity 2) and x = 5 (with multiplicity 1). The multiplicity affects how the graph behaves at these points—at x=2, the graph touches and turns around (because of even multiplicity), and at x=5, it crosses the x-axis (because of odd multiplicity).
Use the information about degree, leading coefficient, end behavior, and zeros to match the function to the correct graph among choices A–F, focusing on the shape near the zeros and the overall direction of the graph.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Polynomial Function and Degree

A polynomial function is an expression involving variables raised to whole-number exponents combined using addition, subtraction, and multiplication. The degree of the polynomial is the highest exponent of the variable, which determines the general shape and end behavior of the graph.
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Introduction to Polynomial Functions

Zeros and Their Multiplicities

Zeros of a polynomial are the values of x that make the function equal to zero. The multiplicity of a zero indicates how many times that root is repeated, affecting the graph's behavior at that point: odd multiplicities cross the x-axis, while even multiplicities touch and turn around.
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Finding Zeros & Their Multiplicity

End Behavior of Polynomial Graphs

The end behavior describes how the graph behaves as x approaches positive or negative infinity. It depends on the leading term's degree and coefficient sign: an odd degree with a negative leading coefficient means the graph falls to the right and rises to the left.
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End Behavior of Polynomial Functions