CAIE IGCSE Mathematics Core C2.7.3 Find & use the nth term of the following sequences: (a) linear (b)

Practise finding and using nth-term rules for linear, quadratic and simple cubic sequences from listed terms or formulae.

Exam points

form a linear nth term by using the common difference as the coefficient of n
use an nth-term expression to find early terms or decide whether a value is in the sequence
recognise a simple quadratic sequence from second differences, then write its nth term

[Maximum number: 4]

(a)

These are the first four terms of a sequence.

\begin{array}{llll} 8 & 15 & 22 & 29 \end{array}

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(i)

Find an expression for the nth term.

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7n+1 oe final answer
B1 for 7n+j or kn+1, $k\ne0$ , as final answer, or for 7n+1 seen then spoilt.

(b)

Find the first three terms of the sequence with nth term $n^{2}+5 n$ .

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