EduNinja

[Maximum number: 4]

(a)

Find the nth term of each sequence.

[ 4 ]

(i)

$6, \quad 13, \quad 32, \quad 69, \quad 130, \quad \ldots$

[ 2 ]

$n^{3}+5$ oe final answer

2

B1 for any cubic
or common third differences of 6
(at least 2)
or for correct answer seen and spoilt

(ii)

$100, \quad 50, \quad 25, \quad 12.5, \quad 6.25, \quad \ldots$

[ 2 ]

$100\times2^{1-n}$ oe final answer
B1 for $2^{-n+k}$ oe or $(\frac12)^{n+k}$ oe in answer, or for correct answer seen and spoilt

[Maximum number: 6]

The table shows the first 5 terms of sequences A, B and C.

Complete the table to show the nth term of each sequence.

f(x)=5-4 x

$n^3+4$ oe final answer
$\frac{11-n}{n+2}$ oe final answer
$2^{n+1}$ oe final answer
B2/B1 alternatives for each sequence as in official markscheme

[Maximum number: 2]

Find an expression for the nth term of this sequence.

$\frac17,\ 1,\ 7,\ 49,\ 343,\ 2401,\ldots$

$7^{n-2}$ oe final answer.

M1 for recognition of terms being powers of 7.

CAIE IGCSE Mathematics Extended E2.7 Sequences Topic Practice