√6 > 3√7
True
Given surds are not 'Like surds'. So, to compare them the powers have to be made equal.
Now LCM of 2 and 3 is 6.
⟹ √6 = 612×33
= 6√63
= 6√216 -------------(1)
3√7 = 713×22
= 6√72
= 6√49 -------------(2)
From (1) and (2), 6√216> 6√49
∴ √6 > 3√7