Question

the fifth term of an arithmetic sequence is 23 and the 12th is 72. determine the next three terms and general formula​

Answer 1

first three terms are -5 , 2, and 9

Explanation:

term(n) = a + (n-1)d

term5 = a+ 4d = 23

term12 = a + 11d = 72

subtract them

7d = 49

d = 7

sub into a+4d = 23

a + 28 = 23

a = -5