Edexcel P3 2023 June — Question 6 9 marks

Exam BoardEdexcel
ModuleP3 (Pure Mathematics 3)
Year2023
SessionJune
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicModulus function
TypeGraph y=a|bx+c|+d given: solve equation or inequality
DifficultyStandard +0.3 This is a straightforward modulus function question requiring standard techniques: finding a vertex (trivial substitution), evaluating a composition, solving a linear modulus inequality (split into cases), and solving f(|x|)=0 (requires one extra step of considering ±x). All parts are routine applications of well-practiced methods with no novel insight required, making it slightly easier than average.
Spec1.02g Inequalities: linear and quadratic in single variable1.02l Modulus function: notation, relations, equations and inequalities1.02s Modulus graphs: sketch graph of |ax+b|

6. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{bef290fb-fbac-4c9c-981e-5e323ac7182e-14_752_794_251_639} \captionsetup{labelformat=empty} \caption{Figure 2}
\end{figure} Figure 2 shows a sketch of the graph \(y = \mathrm { f } ( x )\), where $$f ( x ) = 3 | x - 2 | - 10$$ The vertex of the graph is at point \(P\), shown in Figure 2.
  1. Find the coordinates of \(P\)
  2. Find \(\mathrm { ff } ( 0 )\)
  3. Solve the inequality $$3 | x - 2 | - 10 < 5 x + 10$$
  4. Solve the equation $$\mathrm { f } ( | x | ) = 0$$

Question 6:
Part (a):
AnswerMarks Guidance
Answer/WorkingMark Guidance
\((2, -10)\)B1 B1 First B1 for one correct coordinate; second B1 for full correct pair. Allow \(x=..., y=...\); do not accept e.g. 6/3 unless 2 identified
Part (b):
AnswerMarks Guidance
Answer/WorkingMark Guidance
\(\text{ff}(0) = \text{f}(-4) = ...\)M1 Full attempt at ff(0); may score for f(-4); allow slips with modulus if intent clear
\(= 8\)A1cso ff(0) = 8 only; A0 if other values given
Part (c):
AnswerMarks Guidance
Answer/WorkingMark Guidance
Attempts to solve \(-3(x-2)-10 = 5x+10 \Rightarrow x = ...\)M1 Allow equality or any inequality; alternatively rearranges to \(
\(x > -\frac{7}{4}\) onlyA1 oe only; if another inequality or value given and not rejected, withhold mark
Part (d):
AnswerMarks Guidance
Answer/WorkingMark Guidance
\(x\left(\text{or }x \right) = \frac{16}{3}\)
Attempts \(3(x -2)-10=0 \Rightarrow
\(x = \frac{16}{3}\) and \(-\frac{16}{3}\) with no other valuesA1 Must give negative value, not just \(
# Question 6:

## Part (a):

| Answer/Working | Mark | Guidance |
|---|---|---|
| $(2, -10)$ | B1 B1 | First B1 for one correct coordinate; second B1 for full correct pair. Allow $x=..., y=...$; do not accept e.g. 6/3 unless 2 identified |

## Part (b):

| Answer/Working | Mark | Guidance |
|---|---|---|
| $\text{ff}(0) = \text{f}(-4) = ...$ | M1 | Full attempt at ff(0); may score for f(-4); allow slips with modulus if intent clear |
| $= 8$ | A1cso | ff(0) = 8 only; A0 if other values given |

## Part (c):

| Answer/Working | Mark | Guidance |
|---|---|---|
| Attempts to solve $-3(x-2)-10 = 5x+10 \Rightarrow x = ...$ | M1 | Allow equality or any inequality; alternatively rearranges to $|x-2| = ax+b$, squares and solves |
| $x > -\frac{7}{4}$ only | A1 | oe only; if another inequality or value given and not rejected, withhold mark |

## Part (d):

| Answer/Working | Mark | Guidance |
|---|---|---|
| $x\left(\text{or }|x|\right) = \frac{16}{3}$ | B1 | Allow when seen even from incorrect working; allow also for $|x| = \frac{16}{3}$ |
| Attempts $3(|x|-2)-10=0 \Rightarrow |x|=k$, $k>0$ or $3(-x-2)-10=0 \Rightarrow x=-k$ or $3(x-2)-10=0 \Rightarrow x=k \Rightarrow x=-k$ | M1 | Correct method to find root on negative $x$-axis; allow missing brackets |
| $x = \frac{16}{3}$ and $-\frac{16}{3}$ with no other values | A1 | Must give negative value, not just $|x|=\frac{16}{3}$; may be on sketch if referred to in (d) |

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6.

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{bef290fb-fbac-4c9c-981e-5e323ac7182e-14_752_794_251_639}
\captionsetup{labelformat=empty}
\caption{Figure 2}
\end{center}
\end{figure}

Figure 2 shows a sketch of the graph $y = \mathrm { f } ( x )$, where

$$f ( x ) = 3 | x - 2 | - 10$$

The vertex of the graph is at point $P$, shown in Figure 2.
\begin{enumerate}[label=(\alph*)]
\item Find the coordinates of $P$
\item Find $\mathrm { ff } ( 0 )$
\item Solve the inequality

$$3 | x - 2 | - 10 < 5 x + 10$$
\item Solve the equation

$$\mathrm { f } ( | x | ) = 0$$
\end{enumerate}

\hfill \mbox{\textit{Edexcel P3 2023 Q6 [9]}}