Surds (Edexcel IGCSE Further Pure Maths): Exam Questions

Exam code: 4PM1

20 mins3 questions

4 marks

Expand $\frac{3}{\sqrt{1 - 2 x}}$ in ascending powers of $x$ up to and including the term in $x^{3}$

and simplifying each term as far as possible.

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1 mark

Write down the range of values of $x$ for which this expansion is valid.

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1 mark

Show that $\frac{3}{\sqrt{0.9}} = \sqrt{10}$

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2 marks

Express $\frac{1}{\sqrt{10} - 3}$ in the form $a \sqrt{10} + b$ , where $a$ and $b$ are integers.

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3 marks

Hence, using your expansion with a suitable value for $x$ , obtain an approximation to $5$ decimal places of $\frac{1}{\sqrt{10} - 3}$

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