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Binomial Expansion

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Question 71

The first four terms, in ascending powers of xxx, of the binomial expansion of 1+10x \sqrt{1 + 10x}\,1+10x​ are

1+5x−252x2+1252x3. 1 + 5x - \frac{25}{2}x^2 + \frac{125}{2}x^3. 1+5x−225​x2+2125​x3.

Explain how you could use x=115\displaystyle x = \frac{1}{15}x=151​ in the expansion to find an approximation for 15\sqrt{15}15​. There is no need to carry out the calculation.

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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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