Arithmetic Sequences & Series (Edexcel A Level Maths: Pure): Exam Questions

Exam code: 9MA0

3 hours36 questions
12 marks

Find the next three terms in the following arithmetic sequences:

(i) 30, 18,  6,  ...

(ii) 1 fourth comma space 5 over 12 comma space 7 over 12 comma space 3 over 4 comma space...

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23 marks

A sequence is defined by u subscript n equals 2 n plus 3 where n element of straight natural numbers.

(i) Find the first four terms.

(ii) Find the sum of the first four terms.

(iii) Explain why this sequence is an arithmetic sequence.

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33 marks

In an arithmetic sequence, a is the first term, d is the common difference and u subscript nis the nth term in the sequence.

Find and simplify a formula for u subscript n for the following arithmetic sequences:

(i) 16, 20,  24,  ...

(ii) a equals 3d equals negative 3

(iii) a equals 2, d equals 6

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4
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3 marks

Find the 10th and 20th terms in each of the following arithmetic sequences:

(i) u subscript n equals 4 plus 5 n

(ii) u subscript n equals begin inline style 1 half end style minus begin inline style 1 fourth end style n

(iii) u subscript n equals 50 minus 5 n

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51 mark

An arithmetic sequence has a first term of 3 and a common difference of 4.

Use the formula S subscript n equals n over 2 open square brackets 2 a plus open parentheses n minus 1 close parentheses d close square brackets to find the sum of the first 20 terms.

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1a
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2 marks

In an arithmetic series

  • the first term is 16

  • the 21st term is 24

Find the common difference of the series.

1b
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2 marks

Hence find the sum of the first 500 terms of the series.

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2
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3 marks

A car has six forward gears.

The fastest speed of the car

  • in 1st gear is 28 km h-1

  • in 6th gear is 115 km h-1

Given that the fastest speed of the car in successive gears is modelled by an arithmetic sequence,

find the fastest speed of the car in 3rd gear.

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3a3 marks

The 4th and 8th terms of an arithmetic sequence are 20 and 64 respectively.

Find the first term, a, and the common difference, d.

3b2 marks

The 12th and 16th terms of a different arithmetic sequence differ by 20.

Find the possible values of the common difference.

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4a2 marks

An arithmetic sequence is defined as follows:

  • The first term is 3

  • The 10th term is 30

  • The sum of the first n terms is 630

 Find the common difference.

4b2 marks

Show that n satisfies the equation

n squared plus n minus 420 equals 0

4c2 marks

Hence find the value of n.

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5a5 marks

An arithmetic sequence is defined as follows:

  • The third term is 2

  • The twelfth term is 65

  • The sum of the first n terms is 390

Show that 

7 n squared minus 31 n minus 780 equals 0

5b
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1 mark

Hence find the value of n.

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66 marks

The sum of the first ten terms in an arithmetic series is 40. 

The sum of the first twenty terms in the same series is 280. 

Find the first term, a, and the common difference, d, of the series.

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73 marks

The first three terms in an arithmetic sequence are 

left parenthesis p minus 9 right parenthesis comma space space minus 7 comma space space left parenthesis 9 minus 3 p right parenthesis comma space space horizontal ellipsis

Find the value of p.

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83 marks

The first three terms in an arithmetic sequence are 

negative 1 comma space space left parenthesis q plus 1 right parenthesis comma space space q squared comma space space horizontal ellipsis

Find the possible values of q.

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9a1 mark

An arithmetic sequence is given by

k comma space space 2 k comma space space 3 k comma space space 4 k comma space space...

where k is a constant.

Find a formula for the nth term of the sequence, giving your answer in terms of k and n.

9b2 marks

Show that the sum of the first n terms is given by

fraction numerator k n over denominator 2 end fraction open parentheses n plus 1 close parentheses

9c2 marks

The sum of the first 12 terms is 39.

Find the value of k.

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103 marks

Find the sum of all the odd numbers between 0 and 150:

        1 plus 3 plus 5 plus space horizontal ellipsis plus 149

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113 marks

An arithmetic sequence is given by

left parenthesis 3 q minus 7 right parenthesis comma space space left parenthesis 5 q minus 4 right parenthesis comma space space left parenthesis 7 q minus 1 right parenthesis comma space space horizontal ellipsis space

where q is a constant.

Find an expression for the 100th term of the sequence, giving your answer the form

b q plus c

where b and c are integers to be found.

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123 marks

The first two terms in an arithmetic sequence are left parenthesis p plus 15 right parenthesis and 3. 

The fourth term is left parenthesis 3 p minus 16 right parenthesis.

Find the value of p.

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136 marks

An arithmetic sequence is defined as follows:

  • The third term is 32

  • The eleventh term is 0

  • The sum of the first n terms is negative 44

Find the value of n.

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13 marks

In an arithmetic series, the first term is a and the common difference is d.

Show that

S subscript n equals n over 2 left square bracket 2 a plus left parenthesis n minus 1 right parenthesis d right square bracket

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2a
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2 marks

James saves money over a number of weeks to buy a printer that costs £ 64

He saves £ 10 in week 1, £ 9.20 in week 2, £ 8.40 in week 3 and so on, so that the weekly amounts he saves form an arithmetic sequence.

Given that James takes n weeks to save exactly £ 64, show that

n squared minus 26 n plus 160 equals 0

2b
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1 mark

Solve the equation

n squared minus 26 n plus 160 equals 0

2c
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1 mark

Hence state the number of weeks James takes to save enough money to buy the printer, giving a brief reason for your answer.

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33 marks

The first three terms in an arithmetic sequence are 

left parenthesis q minus 2 right parenthesis comma space space q squared comma space space left parenthesis 4 q plus 5 right parenthesis comma space space horizontal ellipsis

Find the possible values of q.

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45 marks

An arithmetic sequence has

  • a first term of r squared, where r greater than 0

  • a common difference of 3 r

  • a fifth term of 85

Find the ninth term in the sequence.

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5a4 marks

An arithmetic sequence is defined in terms of a constant, k, as follows:

  • The fifth term is k

  • The sum of the first eight terms is 2 k

Show that the first term of the sequence is negative 5 k

5b1 mark

Find an expression for the common difference of the sequence in terms of k only.

5c2 marks

Given that the ninth term of the sequence is 14, find the value of k.

5d2 marks

Find the sum of the first 30 terms of the sequence.

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66 marks

The sum of the first twelve terms in an arithmetic series is 654.

The sum of the first twenty terms in the same arithmetic series is 530.

Find the 21st term in the sequence.

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73 marks

Prove that the sum of the first n odd numbers is a square number, for any positive integer value of n.

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8a5 marks

An arithmetic sequence is defined in terms of a constant, k, as follows:

  • The seventh term is 3 k

  • The sum of the first nine terms is open parentheses 4 k minus 3 close parentheses

Show that the common difference is fraction numerator 23 k plus 3 over denominator 18 end fraction and find an expression for the first term of the sequence, in terms of k only.

8b5 marks

Given that the 19th term of the sequence is 57, find the sum of the first 25 terms.

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94 marks

The first four terms in an arithmetic sequence are 

left parenthesis 2 q minus p right parenthesis comma space space 1 comma space space left parenthesis p minus q right parenthesis comma space space left parenthesis 3 p minus 4 q right parenthesis comma space space horizontal ellipsis

Find the values of p and q.

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10a4 marks

An arithmetic sequence is given by

open parentheses k plus 7 close parentheses comma space space open parentheses 2 k plus 18 close parentheses comma space space open parentheses 3 k plus 29 close parentheses comma space space...

where k is a constant.

If the nth term of the sequence is 36, show that

n equals fraction numerator 40 over denominator k plus 11 end fraction

10b3 marks

Hence show that the sum of the first n terms of the sequence is

 fraction numerator 20 k plus 860 over denominator k plus 11 end fraction

10c2 marks

Given that the sum of the first n terms of the sequence is 180, find the value of k.

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115 marks

The first three terms in an arithmetic sequence are 

2 comma space space 3 q squared comma space space q comma horizontal ellipsis

Given that these first three terms are all positive, find the value of the 40th term in the sequence.

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124 marks

The sum of the first 24 terms in an arithmetic series is nine times the sum of the first two terms in the series.

Find the sum of the first 90 terms in the series.

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13a3 marks

An arithmetic sequence is given by

            left parenthesis negative 21 plus ln space 3 right parenthesis comma space space left parenthesis negative 20 plus ln space 27 right parenthesis comma space space left parenthesis negative 19 plus ln space 243 right parenthesis comma space space horizontal ellipsis

Find, in terms of n, an exact expression for the sum of the first n terms of the sequence.

13b
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2 marks

Hence find the smallest value of n for which the sum of the first n terms is greater than zero.

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1a
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3 marks

Express 2 cos theta plus 8 sin theta in the form R cos open parentheses theta minus alpha close parentheses, where R and alpha are constants, R greater than 0 and 0 less than alpha less than pi over 2.

Give the exact value of R and give the value of alpha in radians to 3 decimal places.

1b3 marks

The first three terms of an arithmetic sequence are

cos space x space space space space space space space space cos space x plus sin space x space space space space space space space space cos space x plus 2 sin space x space space space space space space space space space space space space space x not equal to n pi

Given that S subscript 9 represents the sum of the first 9 terms of this sequence as x varies,

(i) find the exact maximum value of S subscript 9

(ii) deduce the smallest positive value of x at which this maximum value of S subscript 9 occurs.

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24 marks

An arithmetic sequence has

  • a first term of r squared, where r greater than 0

  • a common difference of r

  • a ninth term of 7

S is the set of all the numbers that are in the sequence. 

T is the set of all rational numbers.

Find all the elements in the set S intersection T.

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34 marks

The kth term of an arithmetic series is 0.

The sum of the first n terms is also 0.

Find an expression for n in terms of k only, showing your working clearly.

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4
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7 marks

For an arithmetic series

  • the sum of the first 20 terms is 290

  • the sum of the first 24 terms is -180

  • the sum of the first  n terms is S subscript n

Find the greatest value that S subscript n can take, for any positive integer n.

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55 marks

The nth term in an arithmetic sequence is

open parentheses n plus 1 half close parentheses space ln space 4

Show that the sum of the first n terms of the sequence is given by

ln open parentheses 2 to the power of straight f open parentheses n close parentheses end exponent close parentheses

where straight f open parentheses n close parentheses is a polynomial to be found, in terms of n.

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