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Division of f(x) by x²−x−6 leaves remainder 3x−2. Find f(3).

Read the idea, work independently, then explain what changed.

TOPIC 01

2023 JM01

The remainder is evaluated at 3; it is not itself f(3).

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Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Standard#Your turn

Division of f(x) by x²−x−6 leaves remainder 3x−2. Find f(3).

Official paper · jm01-2023 · I.2 · PDF 2

Official original and suggested answers ↗ · Suggested answer PDF page 5

Skills and prerequisite lessons
  1. Option A−2-2
  2. Option B00
  3. Option C33
  4. Option D77
  5. Option E99

Working and explanation

BUILD THE REASONING

Hint 1
Write the division identity.
Hint 2
The divisor vanishes at x=3.
Worked solution
  1. Introduce the polynomial quotient q.

    f(x)=(x2−x−6)q(x)+3x−2f(x)=(x^2-x-6)q(x)+3x-2
  2. Substitute the root of the divisor.

    f(3)=0q(3)+9−2=7f(3)=0q(3)+9-2=7

D: 7.

Checks and common pitfalls: The remainder is evaluated at 3; it is not itself f(3).

Reasoning checklist · self / teacher assessment
  • Teaching assessment checklist, independently authored. Use the original paper for official marks.
  • Introduce the polynomial quotient q.
    f(x)=(x2−x−6)q(x)+3x−2f(x)=(x^2-x-6)q(x)+3x-2
  • Substitute the root of the divisor.
    f(3)=0q(3)+9−2=7f(3)=0q(3)+9-2=7

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Curriculum and source notes ↗