Below are the first three diagrams in the sequence.
(a)[2]
Fill in the table with the numbers of lines and dots for Diagram 3 and Diagram 4.
(b(i))[1]
Write an expression, in terms of $n$, for the number of lines.
(b(ii))[1]
Write an expression, in terms of $n$, for the number of dots.
(c)[2]
Work out how many lines and dots Diagram 20 contains.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct entries $15,20,16,21$” …
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