Partial fractions then binomial expansion

A question is this type if and only if it asks to first express a rational function in partial fractions, then use binomial expansion to find a series expansion up to a specified term.

33 questions · Standard +0.3

1.02y Partial fractions: decompose rational functions1.04c Extend binomial expansion: rational n, |x|<1
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OCR C4 2006 January Q7
10 marks Standard +0.3
7 The expression \(\frac { 11 + 8 x } { ( 2 - x ) ( 1 + x ) ^ { 2 } }\) is denoted by \(\mathrm { f } ( x )\).
  1. Express \(\mathrm { f } ( x )\) in the form \(\frac { A } { 2 - x } + \frac { B } { 1 + x } + \frac { C } { ( 1 + x ) ^ { 2 } }\), where \(A , B\) and \(C\) are constants.
  2. Given that \(| x | < 1\), find the first 3 terms in the expansion of \(\mathrm { f } ( x )\) in ascending powers of \(x\).
AQA C4 2013 January Q2
11 marks Standard +0.3
2 It is given that \(\mathrm { f } ( x ) = \frac { 7 x - 1 } { ( 1 + 3 x ) ( 3 - x ) }\).
  1. Express \(\mathrm { f } ( x )\) in the form \(\frac { A } { 3 - x } + \frac { B } { 1 + 3 x }\), where \(A\) and \(B\) are integers.
    (3 marks)
    1. Find the first three terms of the binomial expansion of \(\mathrm { f } ( x )\) in the form \(a + b x + c x ^ { 2 }\), where \(a\), \(b\) and \(c\) are rational numbers.
      (7 marks)
    2. State why the binomial expansion cannot be expected to give a good approximation to \(\mathrm { f } ( x )\) at \(x = 0.4\).
      (1 mark)
Edexcel C4 Q7
8 marks Standard +0.3
7. Given that $$\frac { 10 ( 2 - 3 x ) } { ( 1 - 2 x ) ( 2 + x ) } \equiv \frac { A } { 1 - 2 x } + \frac { B } { 2 + x }$$
  1. find the values of the constants \(A\) and \(B\).
  2. Hence, or otherwise, find the series expansion in ascending powers of \(x\), up to and including the term in \(x ^ { 3 }\), of \(\frac { 10 ( 2 - 3 x ) } { ( 1 - 2 x ) ( 2 + x ) }\), for \(| x | < \frac { 1 } { 2 }\).
Edexcel C4 Q3
9 marks Standard +0.3
3. (a) Express \(\frac { 2 + 20 x } { 1 + 2 x - 8 x ^ { 2 } }\) as a sum of partial fractions.
(b) Hence find the series expansion of \(\frac { 2 + 20 x } { 1 + 2 x - 8 x ^ { 2 } } , | x | < \frac { 1 } { 4 }\), in ascending powers of \(x\) up to and including the term in \(x ^ { 3 }\), simplifying each coefficient.
3. continued
AQA FP1 2008 June Q4
9 marks Moderate -0.5
4 [Figure 1 and Figure 2, printed on the insert, are provided for use in this question.]
The variables \(x\) and \(y\) are related by an equation of the form $$y = a x + \frac { b } { x + 2 }$$ where \(a\) and \(b\) are constants.
  1. The variables \(X\) and \(Y\) are defined by \(X = x ( x + 2 ) , Y = y ( x + 2 )\). Show that \(Y = a X + b\).
  2. The following approximate values of \(x\) and \(y\) have been found:
    \(x\)1234
    \(y\)0.401.432.403.35
    1. Complete the table in Figure 1, showing values of \(X\) and \(Y\).
    2. Draw on Figure 2 a linear graph relating \(X\) and \(Y\).
    3. Estimate the values of \(a\) and \(b\).
CAIE P3 2017 November Q8
10 marks Standard +0.3
  1. Express \(\mathrm { f } ( x )\) in partial fractions.
  2. Hence obtain the expansion of \(\mathrm { f } ( x )\) in ascending powers of \(x\), up to and including the term in \(x ^ { 2 }\).
Edexcel C4 Q11
8 marks Moderate -0.3
Given that $$\frac{10(2 - 3x)}{(1 - 2x)(2 + x)} \equiv \frac{A}{1 - 2x} + \frac{B}{2 + x},$$
  1. find the values of the constants \(A\) and \(B\). [3]
  2. Hence, or otherwise, find the series expansion in ascending powers of \(x\), up to and including the term in \(x^3\), of \(\frac{10(2 - 3x)}{(1 - 2x)(2 + x)}\), for \(|x| < \frac{1}{2}\). [5]
OCR C4 Q5
8 marks Standard +0.8
  1. Express \(\frac{2 + 20x}{1 + 2x - 8x^2}\) as a sum of partial fractions. [3]
  2. Hence find the series expansion of \(\frac{2 + 20x}{1 + 2x - 8x^2}\), \(|x| < \frac{1}{4}\), in ascending powers of \(x\) up to and including the term in \(x^3\), simplifying each coefficient. [5]