| Exam Board | Edexcel |
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| Module | C2 (Core Mathematics 2) |
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| Year | 2007 |
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| Session | January |
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| Topic | Binomial Theorem (positive integer n) |
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| Type | Expansion up to x^2 term |
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2. (a) Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 - 2 x ) ^ { 5 }\). Give each term in its simplest form.
(b) If \(x\) is small, so that \(x ^ { 2 }\) and higher powers can be ignored, show that
$$( 1 + x ) ( 1 - 2 x ) ^ { 5 } \approx 1 - 9 x$$
DU