Addition and Subtraction of Expressions Quiz - CBSE Class 8 Mathematics
Free practice quiz: Addition and Subtraction of Expressions (CBSE Class 8 Mathematics). 15 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
This CBSE Class 8 Mathematics practice quiz has 15 multiple-choice questions on Addition and Subtraction of Expressions, and 15 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.
Start quiz: 15 questions, freeLearn the key ideas Beta
Like and Unlike Terms
- Like terms have the same variables raised to the same powers; only their numerical coefficients may differ.
- Only like terms can be added or subtracted. Add or subtract the coefficients and keep the variable part unchanged.
- Unlike terms, such as a and a², or a²b and ab², stay separate in the answer.
Common mistake: Combining unlike terms like a² and a into a³, or adding powers when adding like terms.
Adding Algebraic Expressions
- Write all terms together, keeping each term's own sign, then group like terms.
- Add the coefficients of each group. Arranging terms in descending powers keeps the answer neat.
Common mistake: Dropping the minus sign in front of a term while regrouping, so a negative term wrongly becomes positive.
Subtracting Algebraic Expressions
- To subtract an expression, change the sign of every term in it, then add.
- 'Subtract A from B' means B − A. The expression after 'from' is written first.
Common mistake: Changing the sign of only the first term inside the bracket and leaving the remaining terms unchanged.
Multiplying Brackets by a Number
- A number outside a bracket multiplies every term inside it. This is the distributive property.
- A negative number outside the bracket changes the sign of every term inside it.
- After expanding all brackets, combine the like terms.
Common mistake: Multiplying only the first term inside the bracket by the outside number and forgetting the other terms.
Exam tips
- Underline or colour-code each group of like terms so that no term is missed.
- Check your answer by substituting a small value, like x = 1, into both the question and the answer.
- Write the final answer with terms in descending powers of the variable.
Beta: made with AI and checked by a second AI. A teacher has not reviewed it yet.
Sample questions
Simplify the expression: 3x + 2y - x + 5y
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Answer: A. 2x + 7y
Combine like terms: (3x - x) + (2y + 5y) = 2x + 7y
What is the result of subtracting (3x² - 2x + 5) from (7x² + 4x - 3)?
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Answer: A. 4x² + 6x - 8
(7x² + 4x - 3) - (3x² - 2x + 5) = 7x² + 4x - 3 - 3x² + 2x - 5 = 4x² + 6x - 8
Simplify: (4x³ - 3x² + 2x - 1) - (2x³ + x² - 5x + 3) + (x³ - 2x² + x)
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Answer: A. 3x³ - 6x² + 8x - 4
4x³ - 3x² + 2x - 1 - 2x³ - x² + 5x - 3 + x³ - 2x² + x = 3x³ - 6x² + 8x - 4
From 4m - 3n + 2p, subtract 2m - 4n - p.
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Answer: A. 2m + n + 3p
(4m - 3n + 2p) - (2m - 4n - p) = 4m - 3n + 2p - 2m + 4n + p = 2m + n + 3p
Simplify: 4(a + 2b - c) - 2(a - b + 2c)
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Answer: A. 2a + 10b - 8c
4a + 8b - 4c - 2a + 2b - 4c = 2a + 10b - 8c
More questions in this quiz
Answers and explanations are in the full quiz.
- Subtract (2a - 3b) from (5a + 2b).
- Add 4x² + 5x - 7 and 2x² - 3x + 4
- If A = 2x² - 3x + 1 and B = x² + 2x - 4, find A + B.
- Find the expression that results from subtracting 5x³ + 2x² - 3x + 1 from 8x³ - 4x² + x - 5.
- Let P = 3a³ - 4a²b + 5ab² - 2b³, Q = a³ + 2a²b - 3ab² + b³. Find P - Q and simplify.
- Simplify: (x + y + z) + (2x - y + 3z) - (x - 2y - z)
- What is the sum of 5x³ - 2x² + 4x - 1 and 2x³ + 3x² - x + 5?
- Simplify: 3(2x + y) + 2(x - 3y)
- Subtract (x² - 2xy + y²) from (3x² + 4xy - 2y²)
- If A = 2p³ - 3pq + 4q² and B = p³ + 2pq - q², find 2A - B and simplify.
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