How do you find the 8th term of -1, 1, 3, ...?

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Answer 1 · 2018-03-02T09:18:38

The 8th term in the sequence, #a_8#, is 13.

This appears to be an arithmetic sequence, as the numbers are increasing by 2 each time.

The formula for finding the #n#th term in an arithmetic sequence is:

#a_n=a_1+(n-1)d#

#a_1#, the first term in this sequence is -1.

#d#, or the common difference is 2.

Plug this information into the formula:

#a_n=-1+(n-1)2#

#a_n=2n-3#

Now plug in 8 for #n# to find #a_8#, or the 8th term in the sequence:

#a_8=2(8)-3#

#a_8=13#