How do you find a formula for the nth term of this arithmetic sequence: 15, 27, 39...?

1 Answer
Aug 16, 2015

Answer:

#a_n=3+ 12n #

Explanation:

The sequence is
#15, 27, 39#

The first term:
#color(blue)(a_1=15#

The common difference of this sequence :
#color(blue)(d=27-15=12#

The #nth# term of an arithmetic sequence is given by formula
#color(blue)(a_n=a+(n-1)d#

So #a_n# for this sequence will be :
#a_n=color(blue)(15)+(n-1)color(blue)(12#
#a_n=(15)+ 12n -12#
#a_n=3+ 12n #