Answer:
7. -7.5, 0, 7.5
8. 14.75, 12.5, 10.25, 8, 5.75
Explanation:
You want to fill in the blanks in the indicated arithmetic sequences with the appropriate arithmetic means.
Arithmetic means
The common difference in each arithmetic sequence can be found by dividing the difference between the given values by the number of spaces between those values.
7. -15 ... 15
There are 4 spaces between the given values and the 3 unknowns. The common difference is (15 -(-15))/4 = 7.5. Each blank is 7.5 more than the previous value. The full sequence is ...
-15, -7.5, 0, 7.5, 15
8. 17 ... 3.5
There are 6 spaces between the given values and the 5 unknowns. The common difference is (3.5 -17)/6 = -2.25. Each blank is 2.25 less than the previous value. The full sequence is ...
17, 14.75, 12.5, 10.25, 8, 5.75, 3.5
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