Question

Class 8 Maths MCQ Questions of Linear Equations in One Variable with Answers?

Answer 1

These Class 8 Maths MCQ Questions of Linear Equations in One Variable with Answers have been prepared based on the exam perspective. Linear equations in one variable are the algebraic expressions which have only one variable. These equations are easy to solve. Let us see some of the questions here to practice well. The MCQ Questions for Class 8 with answers have been prepared as per the latest 2021 syllabus, NCERT and examination pattern suggested in Standard 8 by CBSE.

Each problem consisting of four options, out of which one is the correct answer. Students have to solve the problem and select the correct answer.  If practiced MCQ Questions for Class 8 Maths properly can help you to get higher marks. Refer to more Chapter-wise Linear Equations MCQ Questions for Class 8 and also Study more maths formulas for solving equations.

Practice MCQ Question for Class 8 Maths chapter-wise

1. Which of the following is not a linear equation in one variable?

(a) 33z+ 5 = 0
(b) 33 (x+y) = 0
(c) 33x+5 = 0
(d) 33y+5 = 0

2. The solution of 2x-3 = 7 is:

(a) 5
(b) 7
(c) 12
(d) 11

3. The solution of 2y + 9 = 4 is:

(a) 9/2
(b) 4/9
(c) -2/5
(d) -5/2

4. The solution of y/5 = 10 is:

(a) 15
(b) 10
(c) 50
(d) 5

5. What should be added to -7/3 to get 3/7?

(a) 21/58
(b) 58/21
(c) 47/21
(d) 50/21

6. The perimeter of the rectangle is 20cm. If the length of the rectangle is 6cm, then its breadth will be:

(a) 4 cm
(b) 6 cm
(c) 10 cm
(d) 14 cm

7. The age of the father is three times the age of the son. If the age of the son is 15 years old, then the age of the father is:

(a) 55 years
(b) 50 years
(c) 44 years
(d) 45 years

8. The difference between two whole numbers is 66. The ratio of the two numbers is 2: 5. The two numbers are:

(a) 60 and 6
(b) 100 and 33
(c) 110 and 44
(d) 99 and 33

9. Three consecutive integers add up to 51. The integers are:

(a)  16,17,18
(b) 15,16,17
(c) 17,18,19
(d) 18,19,20

10. The solution for 3m = 5m – (8/5) is:

(a) 8/5
(b) 4/5
(c) 5/4
(d) 4/3

11. The degree of x² – 5x + 2 = x³ is:

(a) 3
(b) 2
(c) 1
(d) 0

12. The degree of x² – 9x + 2 = 4x⁴ is:

(a) 3
(b) 2
(c) 1
(d) 4

13. What is the value of x if x + 9 = 12?

(a) 2
(b) 3
(c) 8
(d) 6

14. If a number is divided by 8 it gives 6 as the value. Find the number.

(a) 36
(b) 42
(c) 48
(d) 56

15. Find the value of x if 2x + 10 = 76.

(a) 33
(b) 7.6
(c) 32
(d) 66

16. The perimeter of a rectangle is 40 cm. If its width is 10 cm, then find the length.

(a) 10
(b) 20
(c) 30
(d) 40

17. If x is an even number, then the next even number is:

(a) x+2
(b) x+1
(c) x+4
(d) x+5

18. Nitin was counting down from 32. Sumit was counting upwards, the numbers starting from 1 and he was calling out only the odd numbers. What common number will they call out at the same time if they were calling out at the same speed?

(a) 19
(b) 21
(c) 22
(d) They will not call out the same number

19. Solve 2x − 3 = x + 2

(a) 4
(b) 5
(c) 3
(d) 0

20. Amina thinks of a number and subtracts 5/2 from it. She multiplies the result by 8. The result now obtained is 3 times the same number she thought of. What is the number?

(a) 4
(b) 2
(c) 3
(d) 0

21. The sum of three consecutive multiples of 7 is 357. Find the smallest multiple.

(a) 112
(b) 126
(c) 119
(d) 116

22. The difference between the two numbers is 30. If the bigger number is x, then what is the smaller number?

(a) x – 30
(b) 30 – x
(c) 30x
(d) None of these

23. When a number is added to itself, it becomes 24. What is the number?

(a) 2
(b) 4
(c) 12
(d) 21

24. David cuts bread into two equal pieces and cuts one half into smaller pieces of equal size. Each of the small pieces is twenty grams in weight. If he has seven pieces of the bread all with him, how heavy is the original cake?

(a) 120 gm
(b) 180 gm
(c) 300 gm
(d) 240 gm

25. If x% of 75=12, then the value of x 

(a) 20
(b) 18
(c) 16
(d) 26

Answer 2

1. Answer: (b) 33(x+y) = 0

Explanation: In 33(x+y) = 0, x and y are two variables.

2. Answer: (a) 5

Explanation: 2x-3=7

2x=7+3=10

x=10/2 

= 5

3. Answer: (d) -5/2

Explanation: 2y+9 = 4

2y = 4-9 

= -5

y =-5/2

4. Answer: (c) 50

Explanation: y/5 = 10

y = 5×10 

= 50

5. Answer: (b) 58/21

Explanation: Let the number be x

-7/3+x = 3/7

x=3/7+7/3 

= (9+49)/21 

= 58/21

6. Answer: (a) 4 cm

Explanation: Perimeter of rectangle = 2(Length+Breadth)

20 = 2(6+x)

6+x = 20/2

6+x = 10

x = 10-6

x = 4 cm

7. Answer: (d) 45 years

Explanation: Let the age of the father is x

Given: x = 3 × (age of son)

= 3 × (15) 

= 45 years

8. Answer: (c) 110 and 44

Explanation: Let the two numbers be 2x and 5x since they are in the ratio of 2:5.

The difference between 5x and 2x = 66

5x – 2x = 66

3x = 66

x = 22

Hence, 2x = 2(22) = 44 and 

5x = 5(22) = 110.

9. Answer: (a)  16,17,18

Explanation: Let the three consecutive integers be x, x+1, x+2

x+(x+1)+(x+2) = 51

3x+3 = 51

3x = 51 – 3

x = 48/3 

= 16

x+1 = 16+1

=17

x+2 = x+2 

= 18

10. Answer: (b) 4/5

Explanation: 3m = 5m – (8/5)

8/5 = 5m – 3m

2m = 8/5

m = 8/10 

= 4/5

11. Answer: (a) 3

Explanation: Degree is the highest power of the variable in an equation. Therefore, in the given equation, the highest degree is 3.

12. Answer: (d) 4

Explanation: Degree is the highest power of the variable in an equation. Therefore, in the given equation, the highest degree is 4.

13. Answer: (b) 3

Explanation: x + 9 = 12

x = 12 – 9

x = 3

14. Answer: (c) 48

Explanation: Let X be the number

x/8 = 6

x = 8 x 6 

= 48

15. Answer: (a) 33

Explanation: 2x + 10 = 76

2x = 76 – 10

2x = 66

x = 66/2

x = 33

16. Answer: (a) 10

Explanation: Perimeter of a rectangle = 40 cm

Width = 10 cm

Let the length be x.

Perimeter of rectangle = 2(length + width)

40 = 2 (x + 10)

40/2 = x + 10

20 = x + 10

x = 20 – 10 = 10

Thus, the length is also 10 cm.

Answer 3

 17. Answer: (a) x+2

Explanation:  If x = 2, then 

x + 2 = 2 + 2 

= 4

18. Answer: (d) They will not call out the same number

Explanation: Sumit is counting only 16 odd digits whereas Nitin will be counting 32 digits.
If they count at the same speed Sumit's numbers will finish faster than Nitin and they will never say the same number.

19.  Answer:(b) 5

Explanation: 2x−3 = x+2

⟹2x−x = 2+3

⟹x = 5

20.  Answer: (a) 4

Explanation: \(8(x-\frac{5}{2})=3x\)

8x−20 = 3x

8x−3x = 20

5x = 20

x = 4

Number is 4

21.  Answer: (a) 112

Explanation: Let us take three consecutive multiples of 7 as, 7x,(7x+7),(7x+14)     [x is a natural number]

7x+(7x+7)+(7x+14)=357

⇒ 21x+21=357

⇒ 21(x+1)=357

\(\frac{21(x+1)}{21}=\frac{357}{21}\)  [Diving both sides by 21]

⇒x+1=17

x=17−1

x=16

Hence, the smallest multiple of 7 is 

7 ×16

= 112

22.  Answer: (a) x – 30

Explanation: x – small number = 30

Small number = x – 30

23.  Answer: (c) 12

Explanation: Let the number be x.

x + x = 24

2x = 24

x = 24/2

x = 12

24.  Answer: (d) 240 gm

Explanation: Let the weight of original cake be x.

Then the weight of one half is x/2.

There are a total of seven pieces. 

⇒ The number of smaller pieces  = 6.
As each of the smaller piece weighs 20 grams, the weight of one half is

20 × 6 = 120 grams.

Hence the total weight of the cake 

= 2 ×120 

= 240 grams.

25.  Answer: (c) 16

Explanation: \(\frac{x}{100}\times75=12\)

\(x\times75=12\times100\)

\(x=\frac{12\times100}{75}\)

x = 16

Click here Practice MCQ Question for Linear Equations in One Variable Class 8