[tex]a_2=220,5\\q=1,05\\a_2=a_1\times q\\a_1=a_0\times a_1\\\Rightarrow a_2=a_0\times q^2 \Leftrightarrow a_0=\frac{a_2}{q^2} \\a_0=\frac{220,5}{1,05^2}=\frac{220,5}{1,1025} =200[/tex]
[tex]a_n=a_0\times q^n\\\\\left \{ {{a_0=200} \atop {q=1,05}} \right. \\\\a_n=200\times1,05^n[/tex]
