CAIE P3 2024 June — Question 2 5 marks

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2024
SessionJune
Marks5
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicPartial Fractions
TypeImproper fraction with linear factors – division then partial fractions
DifficultyStandard +0.3 This is a straightforward improper fraction requiring polynomial long division followed by standard partial fractions decomposition. While it involves more steps than a proper fraction, the techniques are routine and well-practiced at A-level, making it slightly above average difficulty but not challenging.
Spec1.02y Partial fractions: decompose rational functions

2 Express \(\frac { 6 x ^ { 2 } - 9 x - 16 } { 2 x ^ { 2 } - 5 x - 12 }\) in partial fractions.

Question 2:
AnswerMarks Guidance
AnswerMark Guidance
State or imply the form \(A + \frac{B}{2x+3} + \frac{C}{x-4}\)B1 \(\frac{Dx+E}{2x+3} + \frac{F}{x-4}\) and \(\frac{P}{2x+3} + \frac{Qx+R}{x-4}\) are also valid
Use a correct method for finding a constantM1 SC: If score B0, they can score M1 A1 for one correct constant. B0 M1 A0 available if they substitute two values to form simultaneous equations but get an incorrect answer, or they substitute one value and make an arithmetic error
Obtain one of \(A = 3\), \(B = -2\) and \(C = 4\)A1 SC: If the horizontal equation is correct apart from an incorrect value for \(A\), the other A marks may be available
Obtain a second valueA1 SC: If denominator factorised as \(\left(x+\frac{3}{2}\right)(x-4)\) can score a maximum of B0 M1 A1 A1 A0 for a split involving 3 terms
Obtain a third valueA1 ISW. Statement of the final split is not required
Alternative Method for Question 2:
AnswerMarks Guidance
AnswerMark Guidance
Divide numerator by denominator(M1)
Obtain \(3\left(+\frac{Px+Q}{2x^2-5x-12}\right)\)(A1) \(\left(3 + \frac{6x+20}{(2x+3)(x-4)}\right)\)
State or imply the form \(\frac{Px+Q}{2x^2-5x-12} = \frac{D}{2x+3} + \frac{E}{x-4}\)(B1) Must deal with the 3 separately or include it correctly on both sides in their split
Obtain one of \(D = -2\) and \(E = 4\)(A1) SC: If denominator factorised as \(\left(x+\frac{3}{2}\right)(x-4)\), then can score a maximum of B0 M1 A1 A1 A0 for a split involving three terms
Obtain a second value(A1) ISW. Statement of the final split is not required
## Question 2:

| Answer | Mark | Guidance |
|--------|------|----------|
| State or imply the form $A + \frac{B}{2x+3} + \frac{C}{x-4}$ | B1 | $\frac{Dx+E}{2x+3} + \frac{F}{x-4}$ and $\frac{P}{2x+3} + \frac{Qx+R}{x-4}$ are also valid |
| Use a correct method for finding a constant | M1 | SC: If score B0, they can score M1 A1 for one correct constant. B0 M1 A0 available if they substitute two values to form simultaneous equations but get an incorrect answer, or they substitute one value and make an arithmetic error |
| Obtain one of $A = 3$, $B = -2$ and $C = 4$ | A1 | SC: If the horizontal equation is correct apart from an incorrect value for $A$, the other A marks may be available |
| Obtain a second value | A1 | SC: If denominator factorised as $\left(x+\frac{3}{2}\right)(x-4)$ can score a maximum of **B0 M1 A1 A1 A0** for a split involving 3 terms |
| Obtain a third value | A1 | ISW. Statement of the final split is not required |

**Alternative Method for Question 2:**

| Answer | Mark | Guidance |
|--------|------|----------|
| Divide numerator by denominator | (M1) | |
| Obtain $3\left(+\frac{Px+Q}{2x^2-5x-12}\right)$ | (A1) | $\left(3 + \frac{6x+20}{(2x+3)(x-4)}\right)$ |
| State or imply the form $\frac{Px+Q}{2x^2-5x-12} = \frac{D}{2x+3} + \frac{E}{x-4}$ | (B1) | Must deal with the 3 separately or include it correctly on both sides in their split |
| Obtain one of $D = -2$ and $E = 4$ | (A1) | SC: If denominator factorised as $\left(x+\frac{3}{2}\right)(x-4)$, then can score a maximum of **B0 M1 A1 A1 A0** for a split involving three terms |
| Obtain a second value | (A1) | ISW. Statement of the final split is not required |

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2 Express $\frac { 6 x ^ { 2 } - 9 x - 16 } { 2 x ^ { 2 } - 5 x - 12 }$ in partial fractions.\\

\hfill \mbox{\textit{CAIE P3 2024 Q2 [5]}}