A geometric sequence has common ratio 4. The second term is 9 more than the first term. What is the first term?
1 Answer
Aug 27, 2017
The first term is
Explanation:
The nth term of a geometric sequence is given by
#t_1 = ar^0 = a#
#t_2 = a + 9#
It's given that the common ratio is
#t_2 = (a)4^1 -> t_2 = 4a #
We now have a system of equations. If we substitute the second equation into the first, we get:
#4a = a + 9#
#3a = 9#
#a = 3#
Let's check our answer. If
Hopefully this helps!