I think you just want the simplest radical form of √192
...if that isn't your question please say so! 
First we want to split 192 into its prime factors.
√192=√2⋅2⋅2⋅2⋅2⋅2⋅3
Then we can rewrite this as:
=√2⋅2⋅√2⋅2⋅√2⋅2⋅√3
Replace each √2⋅2 with 2.
=2⋅2⋅2⋅√3
Multiply the numbers outside the radical together.
=8⋅√3 =8√3
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