{(-3, 7.5) , (-2, 10) , (-1, 12.5)} arithmetic or geomatic

arithmetic

Step-by-step explanation:

The points fall on a straight line. They won't do that for a geometric sequence.

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Normally the terms of either sort of sequence are numbered with counting numbers: 1, 2, 3, Your x-values are negative, so are obviously not term numbers of a sequence. The differences of x-values are 1, and the differences of y-values are 2.5, so we know the x- and y-values are linearly related. That relationship can be expressed in point-slope form by ...

y = 2.5(x +1) +12.5

which can be simplified to

y = 2.5x +15

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The arithmetic sequence with first term 17.5 and common difference 2.5 would be described by this same equation.