Evaluate the given expression at x=6. This is, replace every x in the equation for 6 and solve:
[tex]\begin{gathered} f(6)=600(1+0.1220)^6 \\ f(6)=600(1.1220)^6 \\ f(6)=600\cdot(1.99506) \\ f(6)=1197.04 \end{gathered}[/tex]The balance after 6 months is 1197.04.