Answer:
![a_n=-2-5n](https://img.qammunity.org/2022/formulas/mathematics/high-school/x6xcdrj9r0do2sxxogp7ib8i38nttjqatb.png)
Explanation:
Arithmetic Sequences
The arithmetic sequences are those where any term n is obtained by adding or subtracting a fixed number to the previous term. That number is called the common difference.
The equation to calculate the nth term of an arithmetic sequence is:
![a_n=a_1+(n-1)r](https://img.qammunity.org/2022/formulas/mathematics/college/wuxa8q8rliz34pfcvd4k9jhbj913ekzxla.png)
Where
an = nth term
a1 = first term
r = common difference
n = number of the term
We are given the sequence
-7 -12 -17 -22 -27 ...
The first term of this sequence is a1=-7. We can calculate the common difference by subtracting two consecutive terms:
r = -12 - (-7) = -12 + 7 = -5
The nth term is:
![a_n=-7+(n-1)(-5)](https://img.qammunity.org/2022/formulas/mathematics/high-school/sow87afxmp24laghzhzx61vu3murxjqa27.png)
Multiplying:
![a_n=-7-5n+5](https://img.qammunity.org/2022/formulas/mathematics/high-school/rbymv2rqx6auwsjt8iqks7jaymk9ki6obk.png)
Simplifying:
![\boxed{a_n=-2-5n}](https://img.qammunity.org/2022/formulas/mathematics/high-school/yffa3skq0a63573uwrr73u7jh4ll8wxgf7.png)