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3.1.1 Proof (A-level only)

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Question 40

In the design of a custom optical lens, the focal length $F$ is calculated as the arithmetic mean of a rational base length $L$ and an irrational correction factor $γ\gamma$ .

Given that $\frac{L + \gamma}{2}$ , prove by contradiction that the focal length $F$ must be an irrational number.

[5]

Markscheme

3.1.1 Proof (A-level only) Questions

A Level
Maths
3.1.1 Proof (A-level only)

107 exam-style questions on WJEC A Level Maths 3.1.1 Proof (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

3.1.1 Proof (A-level only)

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3.1.1 Proof (A-level only)

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Question 40

In the design of a custom optical lens, the focal length $F$ is calculated as the arithmetic mean of a rational base length $L$ and an irrational correction factor $γ\gamma$ .

Given that $\frac{L + \gamma}{2}$ , prove by contradiction that the focal length $F$ must be an irrational number.

[5]

Markscheme

3.1.1 Proof (A-level only) Questions

A Level
Maths
3.1.1 Proof (A-level only)

107 exam-style questions on WJEC A Level Maths 3.1.1 Proof (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.