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3.4 Sequences and Series (A-level only)

3.4 Sequences and Series (A-level only)

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Question 13

The function f f\,f is given by

f(x)=1+axf(x) = \sqrt{1 + ax}f(x)=1+ax​

where a a\,a is a non-zero constant.

In the binomial expansion of f(x)f(x)f(x), the coefficients of x x\,x and x2 x^2\,x2 are equal.

a.

Find the value of aaa.

[3]
b(i).

Using this value of aaa, state, using set notation, the values of x x\,x for which the binomial expansion is valid.

[1]
b(ii).

Using this value of aaa, write down the quadratic function that approximates f(x)f(x)f(x) when x x\,x is small.

[1]
Markscheme

3.4 Sequences and Series (A-level only) Questions

  1. A Level
  2. /Maths
  3. /3.4 Sequences and Series (A-level only)

231 exam-style questions on WJEC A Level Maths 3.4 Sequences and Series (A-level only), covering 3.4.1 Sequences and Series (A-level only), 3.4.2 Sequences and Series (A-level only), 3.4.3 Sequences and Series (A-level only), 3.4.4 Sequences and Series (A-level only), 3.4.5 Sequences and Series (A-level only), 3.4.6 Sequences and Series (A-level only), and 3.4.7 Sequences and Series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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