Determine the explicit formula for each arithmetic.

Question

The 9th and 10th yerm of an arithmetic sequence are -24 and -30 respectively.
What is the 30th term?

Answer 1

d = term10 - term
=-30 -(-24) = -6
in a + 8d = -24
a - 48 = -24
a = 24

term30 = a + 29d
= 24 + 29(-6) = -150

the general formula for each term is
term(n) = a + (n-1)d
= 24 + (n-1)(-6)
= 24 - 6n + 6
= -6n + 30