posted by Dee .
Write a formula for the general term (the nth term) of the arithmetic sequence shown below. Do not use a recursion formula. Then use the formula for a'n to find a20, the 20th term of the sequence.
a'1 = -13, d = -5
well, for any A.P., the nth term, Tn is
Tn = a + (n-1)d
So, plug in your numbers.