CAIE P2 2019 March — Question 4 6 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2019
SessionMarch
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicPolynomial Division & Manipulation
TypeDivision then Show Number of Real Roots
DifficultyStandard +0.3 Part (i) is routine polynomial division with verification of remainder—a standard algorithmic procedure. Part (ii) requires recognizing the connection between parts, finding one root by inspection or trial, then using calculus or sign analysis to show uniqueness, which adds modest problem-solving beyond pure recall but remains a familiar exam pattern.
Spec1.02f Solve quadratic equations: including in a function of unknown1.02j Manipulate polynomials: expanding, factorising, division, factor theorem

4
  1. Find the quotient when \(4 x ^ { 3 } + 8 x ^ { 2 } + 11 x + 9\) is divided by ( \(2 x + 1\) ), and show that the remainder is 5 .
  2. Show that the equation \(4 x ^ { 3 } + 8 x ^ { 2 } + 11 x + 4 = 0\) has exactly one real root.

Question 4(i):
AnswerMarks Guidance
AnswerMark Guidance
Carry out division at least as far as \(2x^2 + kx\)M1
Obtain quotient \(2x^2 + 3x + 4\)A1
Confirm remainder is 5A1 Answer given; necessary detail needed
Question 4(ii):
AnswerMarks Guidance
AnswerMark Guidance
State or imply equation is \((2x+1)(2x^2+3x+4) = 0\)B1 FT their quotient from part (i)
Calculate discriminant of 3-term quadratic expression or equivalentM1
Obtain \(-23\) or equiv and conclude appropriatelyA1
## Question 4(i):

| Answer | Mark | Guidance |
|--------|------|----------|
| Carry out division at least as far as $2x^2 + kx$ | M1 | |
| Obtain quotient $2x^2 + 3x + 4$ | A1 | |
| Confirm remainder is 5 | A1 | Answer given; necessary detail needed |

## Question 4(ii):

| Answer | Mark | Guidance |
|--------|------|----------|
| State or imply equation is $(2x+1)(2x^2+3x+4) = 0$ | B1 | FT their quotient from part (i) |
| Calculate discriminant of 3-term quadratic expression or equivalent | M1 | |
| Obtain $-23$ or equiv and conclude appropriately | A1 | |

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4 (i) Find the quotient when $4 x ^ { 3 } + 8 x ^ { 2 } + 11 x + 9$ is divided by ( $2 x + 1$ ), and show that the remainder is 5 .\\

(ii) Show that the equation $4 x ^ { 3 } + 8 x ^ { 2 } + 11 x + 4 = 0$ has exactly one real root.\\

\hfill \mbox{\textit{CAIE P2 2019 Q4 [6]}}