Algebra 2 Practice Test: Polynomial Zeros, Multiplicity and End Behavior
- Polynomial Zeros and End Behavior
- 10 questions
- 13 minutes
These 10 questions connect a polynomial rule to the shape of its graph. Tip: the leading term decides the end behavior, and the multiplicity of a zero decides whether the graph crosses or touches.
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Question 1
Which describes the end behavior of f(x) = −2x5 + 3x2?
Correct answer: A
The leading term −2x5 has odd degree and a negative coefficient, so the graph goes up on the left and down on the right.
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Question 2
Which describes the end behavior of f(x) = 3x4 − 5x3 + 2?
Correct answer: C
The degree is even and the leading coefficient 3 is positive, so both ends point up, like a parabola that opens upward.
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Question 3
At which zero does the graph of f(x) = x(x − 2)2(x + 5) touch the x-axis and turn around?
Correct answer: D
The factor (x − 2)2 gives the zero 2 an even multiplicity, so the graph touches the axis there without crossing. The zeros 0 and −5 have multiplicity 1, so the graph crosses.
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Question 4
Which polynomial has zeros 1, −3 and 4 and a leading coefficient of 1?
Correct answer: B
A zero r gives the factor (x − r). For −3 that is (x + 3). The first option has every sign reversed and would have zeros −1, 3 and −4.
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Question 5
What is the greatest number of turning points the graph of a degree 5 polynomial can have?
Correct answer: D
A polynomial of degree n has at most n − 1 turning points, so a degree 5 polynomial has at most 4.
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Question 6
By the Rational Root Theorem, which number is not a possible rational zero of 2x3 − 5x2 + x − 3?
Correct answer: D
Possible rational zeros are (factors of 3) ÷ (factors of 2): ±1, ±3, ±12, ±32. The number 23 would need 2 to divide the constant and 3 to divide the leading coefficient, which is reversed.
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Question 7
One zero of f(x) = x3 − 4x2 + x + 6 is 3. What are the other zeros?
Correct answer: A
Divide by (x − 3): f(x) = (x − 3)(x2 − x − 2) = (x − 3)(x − 2)(x + 1). The other zeros are 2 and −1.
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Question 8
A polynomial with real coefficients has zeros 2 and 3 + i. Which number must also be a zero?
Correct answer: B
Non-real zeros of a polynomial with real coefficients come in conjugate pairs, so 3 − i is also a zero. Nothing forces −2 to be a zero.
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Question 9
Counting multiplicity and including complex zeros, how many zeros does a polynomial of degree 6 have?
Correct answer: C
By the Fundamental Theorem of Algebra, a degree n polynomial has exactly n complex zeros when repeated zeros are counted by multiplicity.
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Question 10
What does the graph of f(x) = (x + 1)3(x − 4) do at x = −1?
Correct answer: B
The zero −1 has odd multiplicity 3, so the graph crosses the axis, and because the multiplicity is greater than 1 it flattens out, like y = x3 at the origin.
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