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Grade 11 · Math · Algebra 2

11th grade Find all the roots: the Rational Root Theorem, conjugate pairs and Descartes' Rule of Signs worksheet

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Find all the roots: the Rational Root Theorem, conjugate pairs and Descartes' Rule of Signs

Grade 11 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

  1. Esme's robot finds one rational root of x³ + 3x² + 4x + 12. What are all its roots?

  2. Jun finds that 3x³ + 2x² + 3x + 2 has one rational root. What are all its roots?

  3. Kira finds one rational root of x³ − 4x² + 25x − 100. What are all its roots?

  4. Milo's robot needs a degree 3 polynomial with real coefficients, leading coefficient 1, and roots -1 and 2 − i. What is it in standard form?

  5. Noah needs a degree 3 polynomial with real coefficients, leading coefficient 1, and roots 3 and -2 + i. What is it in standard form?

  6. Ren needs a degree 3 polynomial with real coefficients, leading coefficient 1, and roots -4 and 1 + 2i. What is it in standard form?

  7. Tala's polynomial has degree 6 and real coefficients. Two roots are 7i and 3 + 8i; every other root is real. How many real roots does it have, counting repeats?

  8. Zee's robot has a degree 7 polynomial with real coefficients. Two roots are 6i and 4 − 8i; the rest are real. How many real roots, counting repeats?

  9. Bo has a degree 5 polynomial with real coefficients. One root is 9i, and every other root is real. How many real roots does it have, counting repeats?

  10. Esme has a degree 10 polynomial with real coefficients. Two roots are 4i and 9 + 2i; the rest are real. How many real roots, counting repeats?

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11th grade Find all the roots: the Rational Root Theorem, conjugate pairs and Descartes' Rule of Signs worksheet – printable
Print: 123456

About this worksheet

Find all the roots of a polynomial. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can list every candidate rational root and test them.
  • I can say how many roots a polynomial has and how many are real.
  • I can find the partner of a complex root and build a polynomial from it.

Standard: A-APR.B.3, N-CN.C.9 (+)

Words to know

candidate: A number worth testing: ± (factor of the constant) ÷ (factor of the leading number).

complex root: A root like 3i or 1 + 2i; it is not on the real number line.

conjugate: The mirror partner of a + bi: a − bi.

Fundamental Theorem of Algebra: A degree n polynomial has n roots, counting repeats and complex ones.

sign change: Neighboring coefficients with opposite signs, read left to right.

Common mistakes

Counted only the roots the graph shows and left out the complex ones.

Counted a repeated root once.

Solved x² = -9 as x = 3 or -3.

What to say

Ask: a degree 4 polynomial has how many roots in all?

Ask: how many times does x + 1 appear in (x + 1)³?

Ask: what is 3 × 3, and what is (-3) × (-3)?

Questions parents ask

What is the most common mistake with find all the roots: the rational root theorem, conjugate pairs and descartes' rule of signs?

Counted only the roots the graph shows and left out the complex ones.

How can I help my child with find all the roots: the rational root theorem, conjugate pairs and descartes' rule of signs?

Ask: a degree 4 polynomial has how many roots in all?

Are these 11th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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