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Binomial Expansion

Binomial Expansion

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Question 203
a.

The first three terms, in ascending powers of xxx, of the binomial expansion of

1a+bx \frac{1}{\sqrt{a+bx}} a+bx​1​

are

2−13x+112x2 2-\frac{1}{3}x+\frac{1}{12}x^2 2−31​x+121​x2

Find the values of a a\,a and bbb.

[4]
bi.

Without evaluating your expansion, state, giving a reason, which of the three values x=4x=4x=4, x=2x=2x=2 and x=1x=1x=1 should not be used.

[1]
bii.

Without evaluating your expansion, state, giving a reason, which of the three values x=4x=4x=4, x=2x=2x=2 and x=1x=1x=1 would lead to the most accurate approximation to 3\sqrt{3}3​

[1]
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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