The second term of an arithmetic sequence is 35 and the fifth term is −10 − 10 . What is the first term?

Answer 1

a1 = 50

a2 = 35

a3 = 20

a4 = 5

a5 = -10

common difference = -15

an = a1 + (n-1)d

a5 =-10 = a1 + (4)(-15)

-10 = a1 -60

a1 = -10+60 = 50