Question

Given this arithmetic sequence, what is a18 18,14,10

Answer 1

$a_1=18 \\ a_2=14 \\ d=a_2-a_1=14-18=-4 \\ \\ a_n=a_1+d(n-1) \\\\ a_{18}=18+(-4)(18-1) \\ {} \ \ \ \ =18-68 \\ {} \ \ \ \ \boxed{=-50}$