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3.3.7 Sequences and series (A-level only)

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Question 7

The function $f\,$ is given by

$\sqrt{1 + ax}$

where $a\,$ is a non-zero constant.

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

Find the value of $a$ .

[3]

b(i).

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

[1]

b(ii).

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

[1]

Markscheme

3.3.7 Sequences and series (A-level only) Questions

A Level
Maths
3.3.7 Sequences and series (A-level only)

36 exam-style questions on CCEA A Level Maths 3.3.7 Sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

3.3.7 Sequences and series (A-level only)

Question bank

3.3.7 Sequences and series (A-level only)

Easy Medium Hard

1 2 3 4 5 6 7 8

Question 7

The function $f\,$ is given by

$\sqrt{1 + ax}$

where $a\,$ is a non-zero constant.

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

Find the value of $a$ .

[3]

b(i).

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

[1]

b(ii).

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

[1]

Markscheme

3.3.7 Sequences and series (A-level only) Questions

A Level
Maths
3.3.7 Sequences and series (A-level only)

36 exam-style questions on CCEA A Level Maths 3.3.7 Sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.