Binomial Theorem (positive integer n)

330 questions · 31 question types identified

Standard binomial expansion coefficient

Questions asking for a coefficient in the expansion of (a + bx)^n where both terms are simple powers of x (or constants), using the standard binomial theorem directly.

37
11.2% of questions
Show example »
6 Find the coefficient of \(x ^ { 3 }\) in the expansion of \(( 3 - 2 x ) ^ { 5 }\).
View full question →
Product with unknown constant to determine

The product involves a binomial with an unknown constant (like a, b, or c) and the question requires finding this constant given information about a specific coefficient in the product.

29
8.8% of questions
Show example »
1 The coefficient of \(x ^ { 3 }\) in the expansion of \(( 1 + k x ) ( 1 - 2 x ) ^ { 5 }\) is 20 .
Find the value of the constant \(k\).
View full question →
Ratio of coefficients condition

A question is this type if and only if it gives a relationship between two coefficients (e.g., ratio or equality) and asks to find unknown parameters.

26
7.9% of questions
Show example »
1 The coefficients of \(x\) and \(x ^ { 2 }\) in the expansion of \(( 2 + a x ) ^ { 7 }\) are equal. Find the value of the non-zero constant \(a\).
View full question →
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
6.1% of questions
Show example »
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 \(b\).
View full question →
Standard binomial expansion

Expand (a+bx)^n where the expression contains only x as the variable, with no reciprocal terms.

19
5.8% of questions
Single coefficient given directly

The coefficient of a single term is given as a numerical value, and the question asks to find the unknown parameter(s) in the binomial expression.

16
4.8% of questions
Show example »
3 The coefficient of \(x ^ { 2 }\) in the binomial expansion of \(( 1 + a x ) ^ { 6 }\) is \(\frac { 20 } { 3 }\)
View full question →
Single binomial expansion

Questions asking for the constant term in a single binomial expansion of the form (ax^p + b/x^q)^n.

15
4.5% of questions
Show example »
6 Find the constant term in the expansion of \(\left( x ^ { 2 } + \frac { 1 } { x } \right) ^ { 15 }\).
View full question →
Substitution into binomial expansion

A question is this type if and only if it asks to expand (1+u)^n then substitute u = f(x) to find coefficients in the resulting expression.

14
4.2% of questions
Show example »
4
  1. Find the binomial expansion of \(( 2 + x ) ^ { 5 }\), simplifying the terms.
  2. Hence find the coefficient of \(y ^ { 3 }\) in the expansion of \(\left( 2 + 3 y + y ^ { 2 } \right) ^ { 5 }\).
View full question →
Binomial with negative or fractional powers of x

Questions asking for a coefficient in the expansion of expressions like (x + k/x^m)^n or (kx^p + m/x^q)^n, requiring careful tracking of powers when terms contain x in denominators or non-unit powers.

14
4.2% of questions
Show example »
1 Find the coefficient of \(x\) in the expansion of \(\left( 3 x - \frac { 2 } { x } \right) ^ { 5 }\).
View full question →
Standard product of two binomials

Both binomials have positive integer powers and the question asks for a coefficient of x^k in their product, with both binomials expanded in ascending powers of x.

14
4.2% of questions
Show example »
  1. Find the coefficient of \(x ^ { 2 }\) in the expansion of
$$( 1 + x ) ( 1 - x ) ^ { 6 }$$
View full question →
Product with reciprocal term binomial

One binomial contains a reciprocal term (like 1/x or 1/(2x)) which must be expanded first, then multiplied by another binomial to find a coefficient.

14
4.2% of questions
Show example »
2 Find the coefficient of \(x ^ { 2 }\) in the expansion of \(\left( 1 + x ^ { 2 } \right) \left( \frac { x } { 2 } - \frac { 4 } { x } \right) ^ { 6 }\).
View full question →
Numerical approximation using expansion

A question is this type if and only if it asks to use a binomial expansion with a specific value of x to estimate a numerical value.

13
3.9% of questions
Show example »
4
  1. Expand \(( 1 + x ) ^ { 4 }\).
  2. Use your expansion to determine the exact value of \(1002 ^ { 4 }\).
View full question →
Simplify to standard form

Questions that ask to expand and simplify the sum or difference to show it equals a specific form (often with only even powers for sums or odd powers for differences), possibly followed by solving an equation or further application.

13
3.9% of questions
Show example »
1 Simplify \(( 3 + 2 x ) ^ { 3 } - ( 3 - 2 x ) ^ { 3 }\).
View full question →
Expansion up to x^2 term

Questions asking for the first 3 terms in ascending powers of x (up to and including the x^2 term).

13
3.9% of questions
Show example »
Find the first 3 terms, in ascending powers of \(x\), of the binomial expansion of \(( 2 + 3 x ) ^ { 6 }\).
(4)
View full question →
Two equations from coefficients

A question is this type if and only if it provides information about coefficients in two different expansions and asks to solve simultaneous equations for parameters.

10
3.0% of questions
Show example »
4 In the expansion of \(( 3 - 2 x ) \left( 1 + \frac { x } { 2 } \right) ^ { n }\), the coefficient of \(x\) is 7 . Find the value of the constant \(n\) and hence find the coefficient of \(x ^ { 2 }\).
View full question →
Binomial times linear coefficient

The polynomial multiplying the binomial expansion is linear (degree 1), requiring multiplication of the binomial expansion by a simple linear expression like (a + bx).

10
3.0% of questions
Show example »
1 Find the coefficient of \(x ^ { 2 }\) in the expansion of $$( 2 - 5 x ) ( 1 + 3 x ) ^ { 10 }$$
View full question →
Coefficient zero after multiplying binomial

Questions where a binomial expansion is multiplied by a linear or simple factor, and a specific coefficient in the product is set to zero to find unknown constants.

9
2.7% of questions
Show example »
4
  1. Find the first 3 terms in the expansion of \(( 2 - x ) ^ { 6 }\) in ascending powers of \(x\).
  2. Find the value of \(k\) for which there is no term in \(x ^ { 2 }\) in the expansion of \(( 1 + k x ) ( 2 - x ) ^ { 6 }\).
View full question →
Direct binomial expansion then integrate

Questions that ask to expand a single binomial expression and then integrate it directly, without any algebraic manipulation or combination of multiple expansions.

6
1.8% of questions
Show example »
4
  1. Find the binomial expansion of \(\left( x ^ { 2 } - 5 \right) ^ { 3 }\), simplifying the terms.
  2. Hence find \(\int \left( x ^ { 2 } - 5 \right) ^ { 3 } \mathrm {~d} x\).
View full question →
Coefficients in arithmetic/geometric progression

A question is this type if and only if it states that certain coefficients form an arithmetic or geometric sequence and asks to find parameters.

5
1.5% of questions
Show example »
5 In the expansion of \(( a + b x ) ^ { 7 }\), where \(a\) and \(b\) are non-zero constants, the coefficients of \(x , x ^ { 2 }\) and \(x ^ { 4 }\) are the first, second and third terms respectively of a geometric progression. Find the value of \(\frac { a } { b }\).
View full question →
Express result in specific form

A question is this type if and only if it asks to use binomial expansion to express a result in a specific form like a + b√2 or with integer coefficients.

5
1.5% of questions
Show example »
4 In the binomial expansion of \(( \sqrt { } 3 + \sqrt { } 2 ) ^ { 4 }\) there are two irrational terms. Find the difference between these two terms.
View full question →
Find constant from coefficient condition

Questions that give the coefficient of a specific term in the sum or difference of two binomial expansions and ask to find an unknown constant.

5
1.5% of questions
Show example »
2 The coefficient of \(x ^ { 3 }\) in the expansion of \(( 1 - 3 x ) ^ { 6 } + ( 1 + a x ) ^ { 5 }\) is 100 . Find the value of the constant \(a\).
View full question →
Coefficient relationship between terms

The relationship between coefficients of two different terms is given (e.g., one coefficient is double another, or coefficients are equal), and the question asks to find the unknown parameter.

4
1.2% of questions
Show example »
2. (a) Find the first 3 terms, in ascending powers of \(x\), of the binomial expansion of $$( 2 + k x ) ^ { 7 }$$ where \(k\) is a constant. Give each term in its simplest form. Given that the coefficient of \(x ^ { 2 }\) is 6 times the coefficient of \(x\),
(b) find the value of \(k\).
View full question →
Combined expansions then integrate

Questions that require expanding multiple binomial expressions, combining them algebraically (addition or subtraction), and then integrating the simplified result.

4
1.2% of questions
Show example »
5
  1. Using the binomial expansion, or otherwise, express \(( 1 - x ) ^ { 3 }\) in ascending powers of \(x\).
  2. Show that the expansion of $$( 1 + y ) ^ { 4 } - ( 1 - y ) ^ { 3 }$$ is $$7 y + p y ^ { 2 } + q y ^ { 3 } + y ^ { 4 }$$ where \(p\) and \(q\) are constants to be found.
  3. Hence find \(\int \left[ ( 1 + \sqrt { x } ) ^ { 4 } - ( 1 - \sqrt { x } ) ^ { 3 } \right] \mathrm { d } x\), expressing each coefficient in its simplest form.
View full question →
Binomial times quadratic coefficient

The polynomial multiplying the binomial expansion is quadratic (degree 2), requiring multiplication of the binomial expansion by an expression like (a + bx + cx²).

3
0.9% of questions
Show example »
1
  1. Expand \(( 1 + 3 x ) ^ { 6 }\) in ascending powers of \(x\) up to, and including, the term in \(x ^ { 2 }\).
  2. Hence find the coefficient of \(x ^ { 2 }\) in the expansion of \(\left( 1 - 7 x + x ^ { 2 } \right) ( 1 + 3 x ) ^ { 6 }\).
View full question →
Binomial expansion with reciprocals

Expand expressions of the form (x + k/x)^n where both x and 1/x terms appear in the binomial.

3
0.9% of questions
Show example »
2 Expand \(\left( x + \frac { 2 } { x } \right) ^ { 4 }\) completely, simplifying the terms.
View full question →
Product of expansions

Questions asking for the constant term in a product of two or more expressions, where at least one is a binomial expansion, requiring combination of terms from different factors.

3
0.9% of questions
Show example »
4 Find the term that is independent of \(x\) in the expansion of
  1. \(\left( x - \frac { 2 } { x } \right) ^ { 6 }\),
  2. \(\left( 2 + \frac { 3 } { x ^ { 2 } } \right) \left( x - \frac { 2 } { x } \right) ^ { 6 }\).
View full question →
Expansion up to x^3 term

Questions asking for the first 4 terms in ascending powers of x (up to and including the x^3 term).

3
0.9% of questions
Show example »
3. Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of $$\left( 2 - \frac { 1 } { 2 } x \right) ^ { 8 }$$ giving each term in its simplest form.
View full question →
Coefficient zero by design (proof)

Questions that ask to prove or show that a specific coefficient is zero for a given expression with parameters, rather than finding the parameter value.

2
0.6% of questions
Show example »
1 In the expansion of \(\left( 1 - \frac { 2 x } { a } \right) ( a + x ) ^ { 5 }\), where \(a\) is a non-zero constant, show that the coefficient of \(x ^ { 2 }\) is zero.
View full question →
Expansion with algebraic manipulation then integrate

Questions that expand a binomial expression but require dividing by a power of x or other algebraic manipulation before integration.

1
0.3% of questions
Show example »
3
  1. The expression \(\left( 2 + x ^ { 2 } \right) ^ { 3 }\) can be written in the form $$8 + p x ^ { 2 } + q x ^ { 4 } + x ^ { 6 }$$ Show that \(p = 12\) and find the value of the integer \(q\).
    1. Hence find \(\int \frac { \left( 2 + x ^ { 2 } \right) ^ { 3 } } { x ^ { 4 } } \mathrm {~d} x\).
      (5 marks)
    2. Hence find the exact value of \(\int _ { 1 } ^ { 2 } \frac { \left( 2 + x ^ { 2 } \right) ^ { 3 } } { x ^ { 4 } } \mathrm {~d} x\).
      (2 marks)
View full question →
Binomial with negative/fractional powers in terms

A question is this type if and only if the binomial contains terms like x^2 + 1/x or similar, requiring careful tracking of powers.

0
0.0% of questions
Binomial with reciprocal terms coefficient

The binomial itself contains reciprocal terms (like x - 1/x or similar), and is multiplied by a polynomial, requiring careful tracking of powers including negative exponents.

0
0.0% of questions