A series of shapes, made of matchsticks, is shown below. [Figure 20.1] Shape 1 Shape 2 Shape 3 Shape 4

1. (a)Draw Shape 4.[1]
2. (b)The table shows the numbers of matchsticks used to make Shapes 1 and 2. Shape 1 2 3 4 Number of matchsticks 12 18 Complete the table for Shapes 3 and 4.[1]
3. (c)Find an expression, in terms of n, for the number of matchsticks used to make Shape n.[1]
4. (d)Explain why there is not a shape that is made of 100 matchsticks.[1]

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