The following problem refers to an arithmetic sequence. if a_8=9 and a_16=17, Find the term a_1, the common difference d, and then find a_30.
a_n=a_1+(n-1)*d
Just use your formula
a_8=9 ----> a+7d = 9
a_16=17 --> a+15d = 17
subtract them:
8d = 8
= 1
then find d, and finally find term(30)