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Expressions, Equations and IdentitiesEdexcel GCSE Maths: Subtopic test

10 questions, 26 marks

Edexcel GCSE Maths

Expressions, Equations and Identities

Total 26 marks

Name

Class

Date

  1. 1
    A phone repair shop charges a call-out fee of £8 plus cc pounds for every minute of labour, where a repair takes mm minutes.
    (a)
    Which expression gives the cost, in pounds, of a repair taking mm minutes?
    [1 mark]
    • A8+cm8 + cm
    • B8c+m8c + m
    • C8cm8cm
    • D(8+c)m(8 + c)m
    (b)
    Which of the following best describes the relationship 8+cm=Total Cost8 + cm = \text{Total Cost}, given that it is true only for one specific value of mm when the total cost is fixed at 3232?
    [1 mark]
    • AIt is an identity
    • BIt is a formula with no variables
    • CIt is an equation
    • DIt is an expression
    (c)
    If c=3c = 3, simplify the expression for the total cost, 8+3m8 + 3m, by collecting like terms with another repair that costs 8+3m+2m8 + 3m + 2m for a longer job with extra labour minutes mm added twice.
    [1 mark]
    • A16+5m16 + 5m
    • B10+5m10 + 5m
    • C8+6m8 + 6m
    • D8+5m8 + 5m

    Total for question 1: 3 marks

  2. 2
    A gardener is designing a rectangular flower bed. One side has length x+4x + 4 metres and the perpendicular side has length 3x3x metres, so the area, AA, in square metres, is given by A=3x(x+4)A = 3x(x + 4).
    (a)
    Write down the term in xx that results from expanding 3x(x+4)3x(x + 4), and simplify the full expansion.
    [2 marks]
    (b)
    The gardener increases both dimensions so the area becomes A=(x+4)(2x+3)A = (x + 4)(2x + 3). Expand and fully simplify this expression for AA in terms of xx.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A factory manager models the number of faulty items produced per batch, FF, using algebraic expressions in terms of the batch size, nn, measured in hundreds of items.
    (a)
    A factory manager writes the number of faulty items produced per batch as n2−5n+6n^2 - 5n + 6, where nn is the batch size in hundreds. Factorise this expression fully.
    [3 marks]
    (b)
    For a different production line, the manager models faults using 4n2−94n^2 - 9. Show that this expression can be written as (2n−3)(2n+3)(2n-3)(2n+3), and state which factorising technique you have used.
    [3 marks]

    Total for question 3: 6 marks

  4. 4
    A maths teacher sets a worksheet on expressions, equations and identities to check whether her class understands the difference between simplifying, solving and proving.
    (a)
    A teacher asks two students to simplify the expression 5(2x−3)−2(x−4)5(2x - 3) - 2(x - 4). Show full working to fully expand and simplify this expression, giving your answer in the form ax+bax + b.
    [4 marks]
    (b)
    One student claims that 3(x+2)+2(x−1)=5x+43(x + 2) + 2(x - 1) = 5x + 4 is an identity, true for every value of xx. Verify this claim by expanding and simplifying the left-hand side, and state whether the student is correct, explaining your reasoning.
    [4 marks]
    (c)
    The teacher then asks the class to prove that the sum of any three consecutive integers is always a multiple of 33. Using nn, n+1n + 1 and n+2n + 2 to represent the three consecutive integers, prove this result using algebra, showing every step clearly.
    [5 marks]

    Total for question 4: 13 marks

End of questions