To find the 91st term of the arithmetic sequence that starts with -1 and has a common difference of +4, we use the formula for the \(n\)th term of an arithmetic sequence:
\[ a_n = a_1 + (n - 1) d \]
Where:
- \(a_n\) is the \(n\)th term,
- \(a_1\) is the first term,
- \(d\) is the common difference,
- \(n\) is the term number.
In your case:
- \(a_1 = -1\)
- \(d = 4\)
- \(n = 91\)
Now plug in the values:
\[ a_{91} = -1 + (91 - 1) \times 4 \] \[ a_{91} = -1 + 90 \times 4 \] \[ a_{91} = -1 + 360 \] \[ a_{91} = 359 \]
Thus, the 91st term of the sequence is 359.
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