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A13

Sketch translations and reflections of a given function [Higher only]

Higher only

Transforming graphs

Worked answers, methods and verified real exam appearances for A13 on Edexcel GCSE Maths 1MA1.

Explanation

  • For y=f(x)+ay=f(x)+a, translate the graph vertically by vector (0a)\begin{pmatrix}0\\a\end{pmatrix}. For y=f(xa)y=f(x-a), translate it horizontally by (a0)\begin{pmatrix}a\\0\end{pmatrix}; the sign inside the function appears opposite to the movement.
  • The graph y=f(x)y=-f(x) is the reflection of y=f(x)y=f(x) in the xx-axis, while y=f(x)y=f(-x) is its reflection in the yy-axis.
  • Track distinctive points, including intercepts and turning points, and preserve the graph's exact shape and scale.
  • A point (p,q)(p,q) provides a reliable coordinate check after transforming.
  • Examiners expect a fully described transformation, including the correct axis or translation vector.
A translation moves every point by the same vector while preserving the graph's shape.

Worked example

The point (p,q)(p,q) lies on y=f(x)y=f(x). Find its image on y=f(x3)2y=f(x-3)-2.

  1. 1.f(x3)f(x-3) translates the graph 33 units right.
  2. 2.Subtracting 22 outside the function translates it 22 units down.
  3. 3.Therefore (p,q)(p,q) maps to (p+3,q2)(p+3,q-2).

Answer: The image is (p+3,q2)(p+3,q-2), under translation by (32)\begin{pmatrix}3\\-2\end{pmatrix}.

Common mistakes

  • Don't move f(x3)f(x-3) three units left instead of right.
  • Don't reflect y=f(x)y=f(-x) in the xx-axis rather than the yy-axis.
  • Don't move only selected points and change the graph's shape.

Exam tip

For a translation, state the vector; for a reflection, name the mirror axis.

Worked practice

Q1
Tier 1 · Easy

1

Describe fully the transformation from y=f(x)y=f(x) to y=f(x)+4y=f(x)+4.

(2)

(Total for Question 1 is 2 marks)

Mark scheme

Mark scheme for question 1
QuestionAnswerMarkMark scheme
1
  • Translation by vector (04)\begin{pmatrix}0\\4\end{pmatrix}
2Adding 44 outside the function increases every yy-coordinate by 44 and leaves every xx-coordinate unchanged. This is translation by vector (0,4)(0,4).
Q2
Tier 2 · Standard

2

The point (3,2)(3,-2) lies on y=f(x)y=f(x). Find the corresponding point on y=f(x)y=f(-x) and name the transformation.

(3)

(Total for Question 2 is 3 marks)

Mark scheme

Mark scheme for question 2
QuestionAnswerMarkMark scheme
2
  • (3,2)(-3,-2)
  • Reflection in the yy-axis
3Replacing xx by x-x reverses every xx-coordinate and leaves every yy-coordinate unchanged. Thus (3,2)(3,-2) maps to (3,2)(-3,-2), a reflection in the yy-axis.
Q3
Tier 3 · Hard

3

The point (1,5)(-1,5) lies on y=f(x)y=f(x). Find the corresponding point on y=f(2x)3y=f(2-x)-3, and describe the reflection and translations that produce the new graph.

(4)

(Total for Question 3 is 4 marks)

Mark scheme

Mark scheme for question 3
QuestionAnswerMarkMark scheme
3
  • Corresponding point (3,2)(3,2)
  • Reflect in the yy-axis, translate 22 units right, then translate 33 units down
4If (a,b)(a,b) lies on y=f(x)y=f(x), then f(2x)=bf(2-x)=b when 2x=a2-x=a, so the new xx-coordinate is 2a2-a and the new yy-coordinate is b3b-3. With (a,b)=(1,5)(a,b)=(-1,5) this gives (3,2)(3,2). Since f(2x)=f((x2))f(2-x)=f(-(x-2)), the graph is reflected in the yy-axis, moved 22 units right, and then moved 33 units down.
Q4
Tier 1 · Easy

4

Describe fully the transformation from y=f(x)y=f(x) to y=f(x5)y=f(x-5).

(2)

(Total for Question 4 is 2 marks)

Mark scheme

Mark scheme for question 4
QuestionAnswerMarkMark scheme
4
  • Translation by vector (50)\begin{pmatrix}5\\0\end{pmatrix} (or translation 55 units right)
2Replacing xx by x5x-5 moves every point 55 units to the right without changing its height. This is translation by vector (50)\begin{pmatrix}5\\0\end{pmatrix}.
Q5
Tier 2 · Standard

5

The point (2,4)(-2,4) lies on y=f(x)y=f(x). Find the corresponding point on y=f(x)+1y=-f(x)+1, and describe the transformations.

(3)

(Total for Question 5 is 3 marks)

Mark scheme

Mark scheme for question 5
QuestionAnswerMarkMark scheme
5
  • Corresponding point (2,3)(-2,-3)
  • Reflect in the xx-axis, then translate 11 unit up
3The reflection y=f(x)y=-f(x) keeps the xx-coordinate and changes 44 to 4-4. Adding 11 then changes the height to 3-3, so the point becomes (2,3)(-2,-3). The graph is reflected in the xx-axis and translated 11 unit up.
Q6
Tier 3 · Hard

6

The graph y=g(x)y=g(x) is obtained from y=f(x)y=f(x) by reflecting in the xx-axis and then translating by vector (43)\begin{pmatrix}-4\\3\end{pmatrix}. Write g(x)g(x) in terms of f(x)f(x). The point (2,5)(2,-5) lies on y=f(x)y=f(x). Find its image on y=g(x)y=g(x).

(4)

(Total for Question 6 is 4 marks)

Mark scheme

Mark scheme for question 6
QuestionAnswerMarkMark scheme
6
  • g(x)=f(x+4)+3g(x)=-f(x+4)+3
  • Image (2,8)(-2,8)
4Reflection in the xx-axis gives y=f(x)y=-f(x). Translating 44 units left replaces xx by x+4x+4, and translating 33 units up adds 33, so g(x)=f(x+4)+3g(x)=-f(x+4)+3. The point (2,5)(2,-5) reflects to (2,5)(2,5) and then translates to (2,8)(-2,8).
Q7
Tier 2 · Standard

7

The graph of y=g(x)y=g(x) is a translation of the graph of y=f(x)y=f(x). The point (3,2)(-3,2) on y=f(x)y=f(x) corresponds to (4,1)(4,-1) on y=g(x)y=g(x). Write down the translation vector and write g(x)g(x) in terms of f(x)f(x).

(3)

(Total for Question 7 is 3 marks)

Mark scheme

Mark scheme for question 7
QuestionAnswerMarkMark scheme
7
  • Translation vector (73)\begin{pmatrix}7\\-3\end{pmatrix}
  • g(x)=f(x7)3g(x)=f(x-7)-3
3The xx-coordinate increases by 77 and the yy-coordinate decreases by 33, so the vector is (73)\begin{pmatrix}7\\-3\end{pmatrix}. A shift 77 units right replaces xx by x7x-7, and a shift 33 units down subtracts 33, giving g(x)=f(x7)3g(x)=f(x-7)-3.
Q8
Tier 3 · Hard

8

A point (p,q)(p,q) lies on y=f(x)y=f(x). Find the corresponding point on (i) y=f(x)+4y=-f(x)+4 and (ii) y=(f(x)+4)y=-(f(x)+4). Are the two transformed graphs the same? Give a reason.

(4)

(Total for Question 8 is 4 marks)

Mark scheme

Mark scheme for question 8
QuestionAnswerMarkMark scheme
8
  • (i) (p,4q)(p,4-q)
  • (ii) (p,q4)(p,-q-4)
  • No, the first graph is the reflection in the xx-axis translated 44 units up, while the second is translated 44 units down after reflection
4For (i), reflection in the xx-axis changes qq to q-q, then adding 44 gives 4q4-q. For (ii), the bracket first adds 44 to the output and the outside negative changes q+4q+4 to q4-q-4. No, the images differ vertically by 88 units, so the transformed graphs are not the same.
Q9
Tier 3 · Hard

9

The graph y=f(x)y=f(x) has turning point (2,5)(-2,5) and xx-intercepts (5,0)(-5,0) and (1,0)(1,0). The graph y=g(x)y=g(x) is given by g(x)=f(x4)g(x)=-f(x-4). Describe the transformations and find the corresponding turning point and xx-intercepts of y=g(x)y=g(x).

(4)

(Total for Question 9 is 4 marks)

Mark scheme

Mark scheme for question 9
QuestionAnswerMarkMark scheme
9
  • Translate 44 units right, then reflect in the xx-axis
  • Turning point (2,5)(2,-5)
  • xx-intercepts (1,0)(-1,0) and (5,0)(5,0)
4Replacing xx by x4x-4 translates every point 44 units right. The outside negative then reflects every height in the xx-axis. Thus (2,5)(-2,5) maps to (2,5)(2,-5). The intercepts move to (1,0)(-1,0) and (5,0)(5,0); reflection leaves their zero heights unchanged.
Q10
Tier 3 · Hard

10

Higher only: The graph y=g(x)y=g(x) is obtained by reflecting y=f(x)y=f(x) in the yy-axis and then translating it. The point (2,5)(2,5) on y=f(x)y=f(x) maps to (7,1)(-7,1) on y=g(x)y=g(x). Find the translation vector and write g(x)g(x) in terms of f(x)f(x). Find the image of the point (3,2)(-3,-2), which also lies on y=f(x)y=f(x).

(5)

(Total for Question 10 is 5 marks)

Mark scheme

Mark scheme for question 10
QuestionAnswerMarkMark scheme
10
  • Translation vector (54)\begin{pmatrix}-5\\-4\end{pmatrix}
  • g(x)=f(x5)4g(x)=f(-x-5)-4
  • The image of (3,2)(-3,-2) is (2,6)(-2,-6)
5Reflection in the yy-axis maps (2,5)(2,5) to (2,5)(-2,5). Reaching (7,1)(-7,1) then requires translation by (54)\begin{pmatrix}-5\\-4\end{pmatrix}. After reflection the equation is y=f(x)y=f(-x); translating 55 units left and 44 units down gives g(x)=f((x+5))4=f(x5)4g(x)=f(-(x+5))-4=f(-x-5)-4. The point (3,2)(-3,-2) reflects to (3,2)(3,-2) and then translates to (2,6)(-2,-6).

Verified exam appearances

SeriesPaperQuestionMarksCalculatorTierLinks
2023-113HQ201AllowedHigherQPMS
2019-111HQ203Non-calculatorHigherQPMS
2021-112HQ184AllowedHigherQPMS
2022-062HQ213AllowedHigherQPMS
2019-063HQ152AllowedHigherQPMS
2024-062HQ212AllowedHigherQPMS
2024-113HQ214AllowedHigherQPMS
2022-113HQ232AllowedHigherQPMS

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