We have
2√3−√3=√3
3√3−2√3=√3
This shows that difference of a term and the preceding term is always same.Hence, the given sequence form an AP.
Here first term a=√3 and common difference d=√3
Therefore,
a4=a+3d=√3+3×√3
⇒a4=4√3
a5=a+4d=√3+4×√3
⇒a5=5√3
a6=a+5d=√3+5×√3
⇒a6=6√3
Hence, the next three terms are
4√3,5√3,6√3