(a) Write an expression for the \(n\)th term of the following sequence. [2]
2 7 12 17 ……………
\(n\)th term = ……………………
(b) The first four diagrams in a sequence are shown below.
Complete the following subtraction. [1]
(c) The first three diagrams in another sequence are shown below.
Give an expression, in terms of \(n\), for the number of dots ( ● ) in Diagram \(n\). You must simplify your expression. [2]
Mark scheme (a)
Scheme
Marks
Comments
\(5n - 3\)
B2
B1 for sight of \(5n\). Mark final answer.
Mark scheme (b)
Scheme
Marks
Comments
17
B1
Mark scheme (c)
Scheme
Marks
Comments
\(2n + 2\) OR \(2(n + 1)\)
B2
If \(2n + 2\) is not their final answer allow B1 for sight of \(2n + 2\) in earlier work. B1 for a correct answer not simplified or incorrectly simplified e.g. \(n + n + 2\).
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