Explicit Formula: a_n=2^(n-1) First Three Terms: a_1=1, a_2=2, and a_3=4
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=2, into this formula.
a_n= 1 * 2^(n-1) ⇔ a_n=2^(n-1)
We already know that a_1=1. To generate the second term, a_2, we will substitute 2 for n.
