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, $a_{8}$ $a_8$ , is 13.

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

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

$a_{n} = a_{1} + (n - 1) d$ $a_n=a_1+(n-1)d$

$a_{1}$ $a_1$ , the first term in this sequence is -1.

$d$ $d$ , or the common difference is 2.

Plug this information into the formula:

$a_{n} = - 1 + (n - 1) 2$ $a_n=-1+(n-1)2$

$a_{n} = 2 n - 3$ $a_n=2n-3$

Now plug in 8 for $n$ $n$ to find $a_{8}$ $a_8$ , or the 8th term in the sequence:

$a_{8} = 2 (8) - 3$ $a_8=2(8)-3$

$a_{8} = 13$ $a_8=13$