The 25th term is 137
Explanation:[tex]\begin{gathered} \text{Given:} \\ a_1\text{ = -7} \\ a_{18}\text{ = 95} \\ a_{25}\text{ = ?} \end{gathered}[/tex]To get the 25th term, we need to find the common difference.
An arithmetic sequence is given as:
[tex]\begin{gathered} a_n=a_1\text{ + (n - 1)d} \\ \text{where a}_1\text{ = first term} \\ n\text{ = number of terms} \\ d\text{ = co}mmon\text{ difference} \end{gathered}[/tex]The formula for the 18th term will be used to find the common difference:
[tex]\begin{gathered} \text{where n = 18} \\ a_{18}=a_1\text{ + (18 - 1)(d)} \\ 95\text{ = -7 + 17d} \\ 95\text{ + 7 = 17d} \\ 102\text{ = 17d} \\ d\text{ = }\frac{102}{17} \\ d\text{ = 6} \end{gathered}[/tex]Now we can find the 25th term:
[tex]\begin{gathered} \text{where n = 25} \\ a_{25}=a_1\text{ + (25 - 1)d} \\ a_{25}=a_1\text{ + 24d} \\ a_{25}=\text{ -7 + 24(6) }=\text{ 144 - 7} \\ a_{25}=\text{ }137 \end{gathered}[/tex]The 25th term is 137
