If the order of the surds and the radicands are same, then the surds are like surds.
i.
Here, the order of 2√13 and 5√13 is same and their radicands are also same.
∴ √52 and 5√13 are like surds.
ii.
Here, the order of 2√17 and 5√3 is same but their radicands are not.
∴ √68 and 5√3 are unlike surds.
iii.
Here, the order of 12√2 and 7√2 is same and their radicands are also same.
∴ 4√18 and 7√2 are like surds.
iv.
Here, the order of 38√3 and 6√3 is same and their radicands are also same.
∴ 19√12 and 6√3 are like surds.
v. 5√22, 7√33
Here, the order of 5√22 and 7√33 is same but their radicands are not.
∴ 5√22 and 7√33 are unlike surds.
vi.
Here, the order of 5√5 and 5√3 is same but their radicands are not.
∴ 5√5 and √75 are unlike surds.