21
QuizMultiple Choice

Modeling with Polynomial Functions: Polynomial Functions — Test

Question 21 • Advanced Algebra: Concepts and Connections

Which statement describes the graph of this polynomial function? f of x is equal to x to the 5th power minus 6 x to the 4th power plus 9 x cubed

Answer
A
The graph touches the x -axis at x is equal to 0 and crosses the x -axis at x is equal to negative 3 .
B
The graph crosses the x -axis at x is equal to 0 and touches the x -axis at x is equal to 3 .
C
The graph touches the x -axis at x is equal to 0 and crosses the x -axis at x is equal to 3 .
D
The graph crosses the x -axis at x is equal to 0 and touches the x -axis at x is equal to negative 3 .

Explanation

Factor the polynomial: f(x) = x³(x² − 6x + 9) = x³(x − 3)². The zero at x = 0 has multiplicity 3, which is odd, so the graph crosses the x-axis there. The zero at x = 3 has multiplicity 2, which is even, so the graph touches the x-axis there. This matches choice B: it crosses at 0 and touches at 3.

AI-written and checked against the verified answer.

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