The 20th term = -34
Explanation:An arithmetic sequence is one which has a common difference.
For example, the sequence below has a common difference of -2, and first term of 4
4, 2, 0, -2........
The first term, a = 4
The common difference, d = 2 - 4 = -2
The formula for nth term of an arithmetic sequence
[tex]\begin{gathered} a_n=a+(n-1)d \\ \\ a_n=4+(n-1)(-2) \\ \\ a_n=4-2n+2 \\ \\ a_n=6-2n \end{gathered}[/tex]The 20th term is:
[tex]\begin{gathered} a_{20}=6-2(20) \\ \\ a_{20}=6-40 \\ \\ a_{20}=-34 \end{gathered}[/tex]The 20th term = -34
