Question

Which is the 25th term of the arithmetic sequence where a1 = 7 and a9 = 55 ?

Answer 1

an arith seq is defined as:

an = a1 + d(n-1)

to determine "d"

an - a1
------ = d
n-1

Answer 2

A) 151
B) 176
C) 199
D) 224

Answer 3

d = 6

Answer 4

yes,very good,d indeed equals 6
now to find a25,just put a1=7,d=6,n=25 in the an equation given in 1st comment....

Answer 5

an = a1 + d(n-1) .... so 25 = 7 + 6(24) ?

Answer 6

perfect

Answer 7

well, a{25} is the name of the 25th term

Answer 8

an = 7 + 6(24) = 25th term

Answer 9

the value of a{25} = 7 + 6(24)

Answer 10

151 ?

Answer 11

yes,u are correct :)
7+144=151

Answer 12

great thanks :)