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Read and learn about arithmetic sequences. Takes notes and answer questions.
(Free Counting 1-100 in Words and Numbers Worksheets)
Number Patterns
Arithmetic Sequences
Examples of Arithmetic Sequences
An arithmetic sequence is a sequence of numbers or terms that show a repeated mathematical pattern where the same amount is added or subtracted again and again.
Here are three examples of arithmetic sequences. In the first, 3 is added each time, to create each successive number in the sequence. In the second, 4 is added each time. In the third, a decreasing arithmetic sequence, 5 is subtracted each time.
Arithmetic Sequence Example 1: {1, 4, 7, 10, 13, …}
Arithmetic Sequence Example 2: {1, 5, 9, 13, 17, …}
Arithmetic Sequence Example 3: {12, 7, 2, -3, …}
The examples above show that within each arithmetic sequence, the same amount, known as the common difference, is always added or subtracted. This makes a number pattern. We can easily work out the next numbers in a sequence, by looking at how far apart the numbers are. For instance, in the second example, above, since the numbers in this sequence are 4 apart, we know that the number which is being added each time must be 4, and thus we know that the next number in the sequence after 17 will be 17 plus 4, which is 21.
Here is another example of an arithmetic sequence, {0, 2, 4, 6, 8, 10, …}. How far apart are the numbers? See if you can work out the next two numbers in the sequence.
Infinite sequences are written with three dots after the numbers as shown, {1, 2, 3, 4, 5, … }. These three dots indicate that the sequence is infinite and continues on and on forever. Three dots are used because it would take up too much space to write a very long list of numbers. Braces {} are used to surround a sequence.
See if you can work out the patterns in the following arithmetic sequences.
Exercise 1:
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$$2\;is\;being\;added\;each\;time.$$$$\;The\;next\;two\;numbers\;$$$$will\; be\;10\;and\; 12.$$

Exercise 2:
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$$5\;is\;being\;added\;each\;time.$$

Exercise 3:
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$$3\; is \;being \;subtracted\;each \;time.$$$$ \;The\;next\;two\;numbers\;$$$$will\; be\;4\;and\; 1.$$

Exercise 4:
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$$4\; is \;being \;subtracted\;each\;time. $$$$\;The\;next\;number\;$$$$will\; be\;-1.\;$$

Exercise 5:
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$$4\; is \;being \;added\;each\;time. $$$$\;The\;next\;two\;numbers\;$$$$will\; be\;20\;and\; 24.$$

Exercise 6:
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$$3\;is\;being\;added\;each\;time.$$$$\;The\;next\;three\;numbers\;$$$$will\; be\;$$$$15,\; 18\;and\; 21.$$

Exercise 7:
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$$2\;is\;being\;subtracted\;each\;time.$$$$ \;The\;next\;two\;numbers\;$$$$will\; be\;6\;and\;4.$$

Exercise 8:
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$$4\; is \;being \;added\;each \;time.$$$$ \;The\;next\;two\;numbers\;$$$$will\; be\;19\;and\;23.$$

Exercise 9:
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$$3\; is \;being \;subtracted\;each\;time. $$$$\;The\;next\;number\;$$$$will\; be\;4.\;$$

Exercise 10:
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$$2\; is \;being \;added\;each\;time. $$$$\;The\;next\;two\;numbers\;$$$$will\; be\;9\;and\; 11.$$

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