3\sqrt{8}+3\sqrt{2}

To simplify this expression, we can factor out a 3 from both terms:

3√8 + 3√2
= 3(√8 + √2)

Next, we simplify the radical terms:

√8 = √(4*2) = 2√2

Now plug this back into the expression:

3(2√2 + √2)
= 3(3√2)
= 3√2 + 3√2
= 6√2

Therefore, 3√8 + 3√2 simplifies to 6√2.