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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 53

For each polynomial function, identify its graph from choices A–F. ƒ(x)=(x-2)2(x-5)
Six graphs labeled A to F show different polynomial curves with x-intercepts at 2 and 5, illustrating various shapes and turning points.

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Start by identifying the degree of the polynomial function ƒ(x) = (x-2)^2(x-5). Since (x-2)^2 is squared, it contributes degree 2, and (x-5) contributes degree 1, so the total degree is 2 + 1 = 3.
Determine the leading term by multiplying the highest degree terms from each factor: (x)^2 * (x) = x^3. This tells us the polynomial is cubic with a positive leading coefficient, so the end behavior will be: as x → ∞, ƒ(x) → ∞ and as x → -∞, ƒ(x) → -∞.
Identify the zeros of the function from the factors: x = 2 (with multiplicity 2) and x = 5 (with multiplicity 1). The multiplicity affects the graph's behavior at these points.
Analyze the behavior at each zero: at x = 2, since the multiplicity is even (2), the graph will touch the x-axis and turn around (bounce off) at this point; at x = 5, with multiplicity 1 (odd), the graph will cross the x-axis.
Use this information to match the graph: look for a cubic graph that crosses the x-axis at 5, touches and bounces at 2, and has the end behavior of going down to the left and up to the right.

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Key Concepts

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

Polynomial Functions and Their Graphs

A polynomial function is an expression involving variables raised to whole-number exponents combined using addition, subtraction, and multiplication. Its graph is a smooth curve with no breaks, and the degree of the polynomial determines the general shape and number of turning points.
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Zeros and Their Multiplicities

The 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: even multiplicities cause the graph to touch and turn around, while odd multiplicities cause it to cross the x-axis.
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Finding Zeros & Their Multiplicity

End Behavior of Polynomial Functions

End behavior describes how the graph behaves as x approaches positive or negative infinity. It depends on the leading term's degree and coefficient: for example, an odd-degree polynomial with a positive leading coefficient falls to the left and rises to the right, guiding the overall shape of the graph.
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End Behavior of Polynomial Functions