Mathematics questions, chapter 6
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Linear equations
40 marks. Use Practice to check each answer as you go, or Exam to answer everything first. Do not use a calculator. Show your working for Section B.
Section A: objective questions
12 marksChoose the correct answer.
1
Question 1
Which of the following is a linear equation in one variable?
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C
2(m − 3) = 10 has one variable, m, with power 1. 3x + 2 = 4y has two variables, k² has power 2, and 5a − 4 has no equals sign, so it is an expression, not an equation.
2
Question 2
Three times a number, minus 4, is 20. Let the number be x. Which equation shows this?
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B
First multiply the number by 3 to get 3x, then subtract 4: 3x − 4 = 20. 3(x − 4) subtracts 4 before multiplying, and 4 − 3x subtracts in the wrong order.
3
Question 3
Diagram 1 shows a level balance. Each box has a mass of x balls. Find the value of x.
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A
3x + 3 = 21. Take 3 balls from both sides: 3x = 18. Divide both sides by 3: x = 6. 8 comes from adding 3 instead of subtracting, 18 forgets to divide by 3, and 4 divides before subtracting.
4
Question 4
Diagram 2 shows the operations on a number x. Use backtracking to find x.
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D
Undo in reverse order: 18 + 6 = 24, then 24 ÷ 4 = 6. Check: 6 × 4 − 6 = 18 ✓. 3 comes from 18 − 6 (the wrong inverse), 10.5 is 18 ÷ 4 + 6 (wrong order), and 78 is 18 × 4 + 6 (the operations were not reversed).
5
Question 5
Solve 2x − 43 = 6.
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C
Multiply both sides by 3: 2x − 4 = 18. Add 4: 2x = 22. Divide by 2: x = 11. 3 comes from dividing 6 by 3 instead of multiplying, 7 from subtracting 4 instead of adding, and 22 forgets to divide by 2.
6
Question 6
Solve 3(x − 2) = x + 8.
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A
Expand: 3x − 6 = x + 8. Then 3x − x = 8 + 6, so 2x = 14 and x = 7. 5 comes from writing 3x − 2 (not multiplying the 2), 3.5 from adding the x terms (4x = 14), and 14 forgets to divide by 2.
7
Question 7
Which of the following is a linear equation in two variables?
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B
4p − q = 7 has two variables, each with power 1. xy multiplies two variables, 2(k + 3) = 5k has only one variable, and x² has power 2.
8
Question 8
Which ordered pair is a solution of 3x + y = 11?
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D
For (3, 2): 3(3) + 2 = 11 ✓. (2, 3) gives 9 (the values are swapped), (4, 2) gives 14 and (1, 7) gives 10.
9
Question 9
Diagram 3 shows the graph of a linear equation in two variables. Which equation does it represent?
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C
Every point has y 3 more than x: (0, 3), (2, 5), (4, 7). Test (2, 5): 2 − 5 = −3 ✓. In the other equations, (2, 5) gives 7, −3 ≠ 3 and 9.
10
Question 10
Diagram 4 shows the graphs of x − y = −1 and x − y = 2. What type of solution do these simultaneous linear equations have?
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B
The lines are parallel, so they never meet. There is no point on both lines, so there is no solution.
11
Question 11
Diagram 5 shows the graphs of x + y = 5 and x − y = 1. What is the solution of the simultaneous equations?
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A
The lines meet at (3, 2), so x = 3 and y = 2. Check: 3 + 2 = 5 ✓ and 3 − 2 = 1 ✓. (2, 3) swaps the values; (5, 0) and (1, 0) are where each line crosses the x-axis.
12
Question 12
Two pens and one ruler cost RM7.00. One pen and one ruler cost RM4.50. What is the price of one ruler?
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D
2p + r = 7 and p + r = 4.50. Subtract: p = 2.50. Then 2.50 + r = 4.50, so r = RM2.00. RM2.50 is the price of a pen, not the ruler.
Section B: structured questions
28 marksAnswer all questions. Show your working.
13
Question 13
Aminah buys 3 kg of prawns at RMy per kilogram and vegetables for RM10. She pays RM64 altogether.
[1 mark]
(a)Form a linear equation in one variable for this situation.
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Tick each point you got.
[1 mark]
(b)Find the price of 1 kg of prawns.
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Tick each point you got.
[1 mark]
(c)Write a situation for the equation x − 5 = 12, where x is Hafiz's age now.
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Tick each point you got.
14
Question 14
Solve the equation 4x − 3 = 17 in two different ways.
[2 marks]
(a)Use the trial and improvement method. Start with x = 3 and show your trials in a table.
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Tick each point you got.
[2 marks]
(b)Complete the backtracking diagram in Diagram 6 to find x.
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Tick each point you got.
15
Question 15
Diagram 7 shows a rectangle. Its perimeter is 38 cm.
[2 marks]
(a)Form an equation in x and solve it.
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Tick each point you got.
[2 marks]
(b)Find the area of the rectangle.
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16
Question 16
Diagram 8 shows a triangle. The sum of the angles in a triangle is 180°.
[2 marks]
(a)Find the value of x.
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[1 mark]
(b)Find the size of the largest angle.
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17
Question 17
Diagram 9 shows the graph of 2x + y = 4.
[2 marks]
(a)Complete the table of values for 2x + y = 4.
| x | −1 | 0 | 1 | 2 | 3 |
|---|---|---|---|---|---|
| y | 4 | −2 |
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Tick each point you got.
[1 mark]
(b)Use the graph to find the value of y when x = 1.5.
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[1 mark]
(c)Is (4, −4) a solution of 2x + y = 4? Show how you know.
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18
Question 18
Diagram 10 shows an incomplete receipt. A cup of teh tarik costs RM0.60 more than a piece of roti canai. Let the price of a cup of teh tarik be RMt and a piece of roti canai be RMr.
[2 marks]
(a)Form two linear equations in t and r.
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Tick each point you got.
[2 marks]
(b)Find the price of a cup of teh tarik and a piece of roti canai.
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Tick each point you got.
19
Question 19
Ali solved 4(x − 3) = 2x + 6. Diagram 11 shows his working.
[1 mark]
(a)Ali's answer is wrong. In which line is his first mistake? Explain it.
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[2 marks]
(b)Solve the equation correctly and check your answer.
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Tick each point you got.
20
Question 20
Nurul wants to write a word problem for her friends. The answer must be: a burger costs RM4 and a drink costs RM1.
[2 marks]
(a)Write a pair of simultaneous linear equations in b (price of a burger) and d (price of a drink) that has the solution b = 4, d = 1. Show that both equations are satisfied.
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Any pair works if the left sides are not multiples of each other and b = 4, d = 1 makes both true.
Tick each point you got.
[1 mark]
(b)Write the word problem for your equations.
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Tick each point you got.