HMa3 test 1 of 2

I got a question on Wilma: "What does the n:th image mean?".

The letter n is used to describe the position af a term (or picture, depending on exercise) in a sequence. For the first term, n = 1. For the second term,  n = 2 etc.

The expression "the n:th" about a term or picture means it's picked at random. we don't know if it's the third, fifteenth or twentieth or whatever. The point is that in many number sequences, the value if the term can be calculated from the terms position in the sequence. Please have a look here for a good explanation: http://mathcentral.uregina.ca/qq/database/qq.09.04/alex1.html

The same goes for picture sequences like this one:

We see that there are 6 dots in Figure 1, 8 dots in Figure 2 and 10 in Figure 3. The number of dots increase by 2 from a figure to next. We find that the tenth figure will have 24 dots (6, 8, 10, 12, 14, 16, 18, 20, 22, 24).

A way of describing the number of dots in each figure is "four plus twice the figure's number". If we call the figures number n we can write the rule like this 4 + 2n, which is one answer to the last question in the image.

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