The answer is: [tex]3.4x10^{9}Hz[/tex]
Scientific notation is the way that we can write very large or very small number in a simplest way. We can write a number in scientific notation with numbers between 1 and 10, multipliyng it by a power of 10.
In example,
[tex]1Ghz=1000^{3}Hz=1000000000Hz=1x10^{9}Hz[/tex]
So,
[tex]3.4Ghz=34000000Hz=3.4x10^{9}Hz[/tex]
Have a nice day!