Explicit Formula: a_n=-1(-1)^(n-1) First Three Terms: a_1=-1, a_2=1, and a_3=-1
Practice makes perfect
We want to write an explicit formula for the geometric sequence. To do so, we will start by recalling the general formula for a geometric sequence.
a_n=a_1r^(n-1)
Now we will substitute the given values, a_1=-1 and r=-1, into this formula.
a_n= -1 ( -1)^(n-1)
We already know that a_1=-1. To generate the second term, a_2, we will substitute 2 for n.
