First few terms given find parameters

A question is this type if and only if it provides the first few terms of an expansion explicitly and asks to find the values of n and other constants.

20 questions

CAIE P1 2006 June Q4
4 The first three terms in the expansion of \(( 2 + a x ) ^ { n }\), in ascending powers of \(x\), are \(32 - 40 x + b x ^ { 2 }\). Find the values of the constants \(n , a\) and \(b\).
Edexcel C12 2016 January Q7
7. (a) Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 + k x ) ^ { 8 }\), where \(k\) is a non-zero constant. Give each term in its simplest form. Given that the coefficient of \(x ^ { 3 }\) in this expansion is 1512
(b) find the value of \(k\).
Edexcel C12 2017 January Q10
10. The first 3 terms, in ascending powers of \(x\), in the binomial expansion of \(( 1 + a x ) ^ { 20 }\) are given by $$1 + 4 x + p x ^ { 2 }$$ where \(a\) and \(p\) are constants.
  1. Find the value of \(a\).
  2. Find the value of \(p\). One of the terms in the binomial expansion of \(( 1 + a x ) ^ { 20 }\) is \(q x ^ { 4 }\), where \(q\) is a constant.
  3. Find the value of \(q\).
Edexcel C12 2018 January Q15
15. The binomial expansion, in ascending powers of \(x\), of \(( 1 + k x ) ^ { n }\) is $$1 + 36 x + 126 k x ^ { 2 } + \ldots$$ where \(k\) is a non-zero constant and \(n\) is a positive integer.
  1. Show that \(n k ( n - 1 ) = 252\)
  2. Find the value of \(k\) and the value of \(n\).
  3. Using the values of \(k\) and \(n\), find the coefficient of \(x ^ { 3 }\) in the binomial expansion of \(( 1 + k x ) ^ { n }\)
Edexcel C12 2014 June Q8
8. Given that $$1 + 12 x + 70 x ^ { 2 } + \ldots$$ is the binomial expansion, in ascending powers of \(x\) of \(( 1 + b x ) ^ { n }\), where \(n \in \mathbb { N }\) and \(b\) is a constant,
  1. show that \(n b = 12\)
  2. find the values of the constants \(b\) and \(n\).
Edexcel C12 2016 June Q1
  1. The first three terms in ascending powers of \(x\) in the binomial expansion of \(( 1 + p x ) ^ { 8 }\) are given by
$$1 + 12 x + q x ^ { 2 }$$ where \(p\) and \(q\) are constants.
Find the value of \(p\) and the value of \(q\).
Edexcel P2 2023 June Q4
  1. The binomial expansion, in ascending powers of \(x\), of
$$( 3 + p x ) ^ { 5 }$$ where \(p\) is a constant, can be written in the form $$A + B x + C x ^ { 2 } + D x ^ { 3 } \ldots$$ where \(A\), \(B\), \(C\) and \(D\) are constants.
  1. Find the value of \(A\) Given that
    • \(B = 18 D\)
    • \(p < 0\)
    • find
      1. the value of \(p\)
      2. the value of \(C\)
Edexcel P2 2021 October Q1
  1. The first three terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 + k x ) ^ { 16 }\) are
$$1 , - 4 x \text { and } p x ^ { 2 }$$ where \(k\) and \(p\) are constants.
  1. Find, in simplest form,
    1. the value of \(k\)
    2. the value of \(p\) $$g ( x ) = \left( 2 + \frac { 16 } { x } \right) ( 1 + k x ) ^ { 16 }$$ Using the value of \(k\) found in part (a),
  2. find the term in \(x ^ { 2 }\) in the expansion of \(\mathrm { g } ( x )\). $$\begin{aligned} u _ { 1 } & = 6
    u _ { n + 1 } & = k u _ { n } + 3 \end{aligned}$$ where \(k\) is a positive constant.
  3. Find, in terms of \(k\), an expression for \(u _ { 3 }\) Given that \(\sum _ { n = 1 } ^ { 3 } u _ { n } = 117\)
  4. find the value of \(k\).
Edexcel C2 2006 January Q2
2. (a) Find the first 3 terms, in ascending powers of \(x\), of the binomial expansion of $$( 1 + p x ) ^ { 9 }$$ where \(p\) is a constant. These first 3 terms are \(1,36 x\) and \(q x ^ { 2 }\), where \(q\) is a constant.
(b) Find the value of \(p\) and the value of \(q\).
Edexcel C2 2014 January Q1
  1. The first three terms in ascending powers of \(x\) in the binomial expansion of \(( 1 + p x ) ^ { 12 }\) are given by
$$1 + 18 x + q x ^ { 2 }$$ where \(p\) and \(q\) are constants.
Find the value of \(p\) and the value of \(q\).
Edexcel C2 Q7
  1. The first four terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 + k x ) ^ { n }\) are
$$1 + A x + B x ^ { 2 } + B x ^ { 3 } + \ldots$$ where \(k\) is a positive constant and \(A\), \(B\) and \(n\) are positive integers.
  1. By considering the coefficients of \(x ^ { 2 }\) and \(x ^ { 3 }\), show that \(3 = ( n - 2 ) k\). Given that \(A = 4\),
  2. find the value of \(n\) and the value of \(k\).
    7. continuedLeave blank
OCR C2 2012 January Q3
3 One of the terms in the binomial expansion of \(( 4 + a x ) ^ { 6 }\) is \(160 x ^ { 3 }\).
  1. Find the value of \(a\).
  2. Using this value of \(a\), find the first two terms in the expansion of \(( 4 + a x ) ^ { 6 }\) in ascending powers of \(x\).
OCR C2 2011 June Q5
5 The first four terms in the binomial expansion of \(( 3 + k x ) ^ { 5 }\), in ascending powers of \(x\), can be written as \(a + b x + c x ^ { 2 } + d x ^ { 3 }\).
  1. State the value of \(a\).
  2. Given that \(b = c\), find the value of \(k\).
  3. Hence find the value of \(d\).
Edexcel AS Paper 1 2021 November Q8
8. $$g ( x ) = ( 2 + a x ) ^ { 8 } \quad \text { where } a \text { is a constant }$$ Given that one of the terms in the binomial expansion of \(\mathrm { g } ( x )\) is \(3402 x ^ { 5 }\)
  1. find the value of \(a\). Using this value of \(a\),
  2. find the constant term in the expansion of $$\left( 1 + \frac { 1 } { x ^ { 4 } } \right) ( 2 + a x ) ^ { 8 }$$
Edexcel AS Paper 1 Q11
11. The first 3 terms, in ascending powers of \(x\), in the binomial expansion of \(( 1 + k x ) ^ { 10 }\) are given by $$1 + 15 x + p x ^ { 2 }$$ where \(k\) and \(p\) are constants.
a. Find the value of \(k\)
b. Find the value of \(p\)
c. Given that, in the expansion of \(( 1 + k x ) ^ { 10 }\), the coefficient of \(x ^ { 4 }\) is \(q\), find the value of \(q\).
AQA C2 2012 January Q5
5
    1. Describe the geometrical transformation that maps the graph of \(y = \left( 1 + \frac { x } { 3 } \right) ^ { 6 }\) onto the graph of \(y = ( 1 + 2 x ) ^ { 6 }\).
    2. The curve \(y = \left( 1 + \frac { x } { 3 } \right) ^ { 6 }\) is translated by the vector \(\left[ \begin{array} { l } 3
      0 \end{array} \right]\) to give the curve \(y = \mathrm { g } ( x )\). Find an expression for \(\mathrm { g } ( x )\), simplifying your answer.
  1. The first four terms in the binomial expansion of \(\left( 1 + \frac { x } { 3 } \right) ^ { 6 }\) are \(1 + a x + b x ^ { 2 } + c x ^ { 3 }\). Find the values of the constants \(a , b\) and \(c\), giving your answers in their simplest form.
Edexcel C2 Q2
2. (a) Write down the first four terms of the binomial expansion, in ascending powers of \(x\), of \(( 1 + a x ) ^ { n }\), where \(n > 2\). Given that, in this expansion, the coefficient of \(x\) is 8 and the coefficient of \(x ^ { 2 }\) is 30 ,
(b) find the value of \(n\) and the value of \(a\),
(c) find the coefficient of \(x ^ { 3 }\).
Edexcel C2 Q5
5. The expansion of \(( 2 - p x ) ^ { 6 }\) in ascending powers of \(x\), as far as the term in \(x ^ { 2 }\), is $$64 + A x + 135 x ^ { 2 }$$ Given that \(p > 0\), find the value of \(p\) and the value of \(A\).
Edexcel C2 Q5
5. (a) Write down the first 4 terms of the binomial expansion, in ascending powers of \(x\), of $$( 1 + a x ) ^ { n } , n > 2 .$$ Given that, in this expansion, the coefficient of \(x\) is 8 and the coefficient of \(x ^ { 2 }\) is 30 ,
(b) calculate the value of \(n\) and the value of \(a\),
(c) find the coefficient of \(x ^ { 3 }\).
[0pt] [P2 November 2003 Question 3]
Edexcel C2 Q4
4. The first three terms in the expansion in descending powers of \(x\) of $$\left( x + \frac { k } { x ^ { 2 } } \right) ^ { 15 } ,$$ where \(k\) is a constant, are $$x ^ { 15 } + 30 x ^ { 12 } + A x ^ { 9 } .$$
  1. Find the values of \(k\) and \(A\).
  2. Find the value of the term independent of \(x\) in the expansion.