Example 2: What is the common ratio of the sequence 1, 2, 4, 8,……..?

Solution: We have

a1=1, a2=2, a3=4, a4=8

$ \displaystyle r=\frac{{{{a}_{2}}}}{{{{a}_{1}}}}=\frac{{{{a}_{3}}}}{{{{a}_{2}}}}=\frac{{{{a}_{4}}}}{{{{a}_{3}}}}$

$ \displaystyle r=\frac{2}{1}=\frac{4}{2}=\frac{8}{4}=2$

Therefore the **common ratio** is **2**.