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Binomial Expansion

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Question 48

A student substitutes x=12\displaystyle x = \frac{1}{2}x=21​ into the expansion

1+4x1−x≈1+52x−58x2 \sqrt{\frac{1+4x}{1-x}} \approx 1 + \frac{5}{2}x - \frac{5}{8}x^2 1−x1+4x​​≈1+25​x−85​x2

to find an estimate for 6\sqrt{6}6​. Give a reason why the student should not use x=12\displaystyle x = \frac{1}{2}x=21​

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Markscheme

Binomial Expansion Questions

  1. A Level
  2. /Maths
  3. /Binomial Expansion

408 exam-style questions on Edexcel A Level Maths Binomial Expansion, covering 4.1 Expanding (1 + x)^n, 4.2 Expanding (a + bx)^n, and 4.3 Using Partial Fractions. Each one has a worked solution and a mark scheme showing where the marks go.

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