The fifth term of an arithmetic sequence is 9 and the 32nd term is -84. What is the 23rd term?
We have that a5=9
This means that +d(5−1)=9 or a1+4d=9.
We have that a32=−84.
This means that a1+d(32−1)=−84 or a1+31d=−84.
We have that d=−319.
We obtained the following system:
Solving it, we obtain that a1=205/9, d=-31/9.