Generating sequences Worked Solutions — GCSE Maths

Fully worked, step-by-step solutions to GCSE Generating sequences questions. See exactly how to solve problems on term-to-term rule, generating terms, continuing a sequence, position-to-term rule.

term-to-term rulegenerating termscontinuing a sequenceposition-to-term rulenth term substitutiondecreasing sequence
GCSE Foundation70 questionsStep-by-step solutions
Question 1
1 markeasy
The first term of a sequence is 55. The term-to-term rule is 'add 44'. Write down the second term.

Worked solution

  1. Write down the first term

    a1=5a_1 = 5

    The sequence starts at 5.

  2. Apply the term-to-term rule 'add 4'

    a2=5+4a_2 = 5 + 4

    A term-to-term rule tells you how to get from one term to the NEXT one: add 4 to the term before.

  3. Work out the second term

    a2=9a_2 = 9

    5 add 4 is 9, so the second term is 9.

Answer
99
Question 2
2 markseasy
The first term of a sequence is 22. The term-to-term rule is 'add 77'. Work out the third term.

Worked solution

  1. Write down the first term

    a1=2a_1 = 2

    The sequence starts at 2.

  2. Find the second term

    a2=2+7=9a_2 = 2 + 7 = 9

    Add 7 to the first term.

  3. Find the third term

    a3=9+7=16a_3 = 9 + 7 = 16

    Add 7 again — this time to the SECOND term, not to the first.

Answer
1616
Question 3
1 markeasy
Here are the first four terms of a sequence. 3, 7, 11, 15, 3,\ 7,\ 11,\ 15,\ \ldots The term-to-term rule is 'add 44'. Write down the next term.

Worked solution

  1. Find the last term you are given

    1515

    The next term is built from the term you already have at the end.

  2. Apply the rule to that term

    15+415 + 4

    The rule says add 4 to the previous term.

  3. Work out the next term

    15+4=1915 + 4 = 19

    The next term is 19.

Answer
1919
Question 4
1 markeasy
The nnth term of a sequence is 4n+14n + 1. Work out the first term.

Worked solution

  1. Write down the position-to-term rule

    4n+14n + 1

    Here n stands for the POSITION of the term: n=1n = 1 for the first term, n=2n = 2 for the second, and so on.

  2. Substitute n=1n = 1

    4×1+14 \times 1 + 1

    The first term means the term in position 1.

  3. Work out the value

    4+1=54 + 1 = 5

    The first term is 5.

Answer
55
Question 5
2 markseasy
The nnth term of a sequence is 3n+23n + 2. Work out the 55th term.

Worked solution

  1. Write down the position-to-term rule

    3n+23n + 2

    n is the position number of the term you want.

  2. Substitute n=5n = 5

    3×5+23 \times 5 + 2

    For the 5th term you put 5 in place of n.

  3. Work out the value

    15+2=1715 + 2 = 17

    Multiply before you add, so the 5th term is 17.

Answer
1717

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