Composite functions
Edexcel GCSE Maths revision on Composite functions. Aligned to the Pearson Edexcel GCSE Mathematics 1MA1 specification. This bank has 16 practice questions on this topic.
Sample questions (3 of 16)
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Question 1
Given f(x) = 2x and g(x) = x + 3, what is the value of fg(2)?
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Answer: 10
First, evaluate g(2) = 2 + 3 = 5. Then, substitute 5 into f(x) to get f(5) = 2 multiplied by 5, which equals 10.
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Question 2
If f(x) = x squared and g(x) = x + 1, which of the following represents gf(x)?
- A) x squared plus one
- B) x plus one squared
- C) x squared minus one
- D) x minus one squared
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Answer: x squared plus one
The notation gf(x) means g(f(x)). Since f(x) = x squared, substituting this into g(x) yields x squared + 1.
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Question 3
Given f(x) = 3x - 1, what is the expression for ff(x)?
- A) 9x minus four
- B) 9x minus two
- C) 3x minus two
- D) 6x minus two
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Answer: 9x minus four
We calculate f(3x - 1) which is 3(3x - 1) - 1. Expanding the brackets gives 9x - 3 - 1, resulting in 9x - 4.
Want to test yourself on the remaining cards for this topic?
13 more questions on Composite functions — plus mistakes tracking and spaced repetition across the whole Maths spec.