Loading...

About Algebraic Expressions — Class 7 Olympiad

Form, simplify, and evaluate algebraic expressions; solve pattern-based and expression manipulation problems. This topic is part of the Olympiad Class 7 mathematics syllabus (chapter: Module 5). On this page you can practice 48 questions across three difficulty levels — 19 easy, 19 medium, and 10 hard — each with a visual step-by-step solution, plus a timed 26-question mastery test with a live leaderboard. Worked examples and sample questions from the topic are below.

Algebraic Expressions — solved examples for Class 7 Olympiad

Example 1easy

Consider the algebraic expression 5x³y² - 7x²y + 2xy² - 9y + 11. What is the sum of the coefficients of all terms that contain 'y'?
  1. A)2
  2. B)-7
  3. C)-9
  4. D)11

Step-by-step solution

  1. The terms containing 'y' in the expression are 5x³y², -7x²y, 2xy², and -9y.
  2. Their respective coefficients are 5, -7, 2, and -9.
  3. To find the sum, add these coefficients: 5 + (-7) + 2 + (-9).
  4. Sum = 5 - 7 + 2 - 9 = -2 + 2 - 9 = 0 - 9 = -9.

Answer: -9

Example 2medium

A rectangular field has length (5x + 2y) meters and width (3x - y) meters. If the cost of fencing is ₹(2x + y) per meter, what is the total cost of fencing the field?
  1. A)₹(16x² + 16xy + 3y²)
  2. B)₹(8x² + 10xy + 3y²)
  3. C)₹(32x² + 20xy + 2y²)
  4. D)₹(16x² + 20xy + 2y²)

Step-by-step solution

  1. Perimeter of the field = 2 × (Length + Width)
  2. P = 2 × [(5x + 2y) + (3x - y)] = 2 × (8x + y) = (16x + 2y) meters.
  3. Cost of fencing per meter = ₹(2x + y).
  4. Total cost = Perimeter × Cost per meter = (16x + 2y) × (2x + y) = 16x(2x) + 16x(y) + 2y(2x) + 2y(y) = 32x² + 16xy + 4xy + 2y² = 32x² + 20xy + 2y².

Answer: ₹(32x² + 20xy + 2y²)

Example 3hard

A sequence of algebraic expressions is defined as follows:
E₁ = x - y
E_n = E_{n-1} + (x + y) if n is even
E_n = E_{n-1} - (x - y) if n is odd and n > 1
What is the simplified form of E₂₀₂₃?
  1. A)x - 2023y
  2. B)2x + 2022y
  3. C)x + 2021y
  4. D)2x - 2020y

Step-by-step solution

  1. Let's list the first few expressions to find the pattern:
    E₁ = x - y
  2. E₂ = E₁ + (x + y) = (x - y) + (x + y) = 2x
  3. E₃ = E₂ - (x - y) = 2x - (x - y) = x + y
  4. E₄ = E₃ + (x + y) = (x + y) + (x + y) = 2x + 2y
  5. E₅ = E₄ - (x - y) = (2x + 2y) - (x - y) = x + 3y
  6. Observing the pattern:
    For odd 'n' (n ≥ 1): E_n = x + (n - 2)y. (E₁ = x - y, E₃ = x + y, E₅ = x + 3y)
  7. For even 'n' (n ≥ 2): E_n = 2x + (n - 2)y. (E₂ = 2x, E₄ = 2x + 2y)
  8. Since 2023 is an odd number, we use the formula for odd 'n':
  9. E₂₀₂₃ = x + (2023 - 2)y
    E2023=x+2021yE₂₀₂₃ = x + 2021y

Answer: x + 2021y

Practice questions on Algebraic Expressions

  1. Q1.easy

    A farmer has 'N' sheep. He sells one-third of them and then buys 15 more. Which algebraic expression represents the number of sheep he now has?
    1. A)N/3 + 15
    2. B)2N/3 + 15
    3. C)N - N/3 - 15
    4. D)N + 15 - 1/3
    Show answer

    Answer: 2N/3 + 15

    Hint: First, calculate the number of sheep remaining after selling. Then, add the number of sheep he bought.

  2. Q2.easy

    Simplify the expression: 7a - [5b - (3a - 2b) + a]
    1. A)3a - 7b
    2. B)5a - 3b
    3. C)9a - 7b
    4. D)9a - 3b
    Show answer

    Answer: 9a - 7b

    Hint: Work from the innermost parentheses outwards, being very careful with negative signs when removing brackets.

  3. Q3.easy

    If x = -2 and y = 3, find the value of (x - y)² - (x² + y²).
    1. A)-12
    2. B)12
    3. C)24
    4. D)-24
    Show answer

    Answer: 12

    Hint: Substitute the given values for 'x' and 'y' into the expression. Pay close attention to the order of operations and the signs of numbers being squared.

  4. Q4.medium

    If x + 1/x = 4, what is the value of x² + 1/x²?
    1. A)12
    2. B)14
    3. C)16
    4. D)18
    Show answer

    Answer: 14

    Hint: Consider squaring the given equation (x + 1/x = 4) on both sides. Remember the algebraic identity for (a+b)².

  5. Q5.medium

    Consider the sequence of expressions: 2x+1, 5x+4, 8x+7, ... If the pattern continues, what is the 10th term in this sequence?
    1. A)29x + 27
    2. B)30x + 28
    3. C)29x + 28
    4. D)32x + 31
    Show answer

    Answer: 29x + 28

    Hint: Observe the pattern for the coefficients of 'x' and the constant terms separately. Both form arithmetic progressions.

  6. Q6.medium

    When the product (2x - 3y + 4)(x + 2y - 1) is expanded, what is the coefficient of the term 'xy'?
    1. A)-4
    2. B)-1
    3. C)7
    4. D)1
    Show answer

    Answer: 1

    Hint: To find the coefficient of 'xy', you only need to consider the products of terms that result in 'xy'. Multiply the 'x' terms from the first expression with 'y' terms from the second, and vice-versa.

  7. Q7.hard

    An algebraic expression P was first multiplied by (3x), then (5y) was added to the result. Finally, the entire expression was multiplied by 2, yielding (6x² + 10xy + 10y). What was the original expression P?
    1. A)x + 2y
    2. B)2x + y
    3. C)x + (3/5)y
    4. D)x + (5/3)y
    Show answer

    Answer: x + (5/3)y

    Hint: Work backwards through the operations, performing the inverse operation at each step.

  8. Q8.hard

    A student simplified the expression (4x² - 3x + 7) - (ax² + bx - c). Due to a sign error, they incorrectly added the second expression instead of subtracting it. Their incorrect simplified result was 6x² + 2x - 1. What would have been the correct simplified expression?
    1. A)2x² + 5x - 1
    2. B)2x² - 8x + 15
    3. C)6x² - 5x + 15
    4. D)4x² - 8x + 1
    Show answer

    Answer: 2x² - 8x + 15

    Hint: First, use the incorrect result to find the values of a, b, and c. Then, apply the correct subtraction with these values.

  9. Q9.hard

    If the expression (ax² + 5x - 3) - (2x² - bx + 7) + (cx² - 4x + 10) simplifies to an expression that is independent of x, what is the value of a + b + c?
    1. A)1
    2. B)0
    3. C)2
    4. D)-1
    Show answer

    Answer: 1

    Hint: For an expression to be independent of x, the coefficients of all terms containing x must be zero.

These are 9 of the 48 questions available for Algebraic Expressions. Start practicing above to unlock visual solutions, AI coaching, and the topic leaderboard — completely free.