1. Determine the periodicity of \(x + \sin 2x\):
- \(\sin 2x\) has a period of \(\pi\).
- The term x is not periodic.
- Because the sum of a periodic function (\(\sin 2x\)) and a non-periodic function (x) is not periodic, \(x + \sin 2x\) is not periodic.
2. Determine the periodicity of \(\cos(\sqrt{x} + 1)\):
- \(\sqrt{x}\) is not periodic.
- Adding 1 to \(\sqrt{x}\) doesn't change its non-periodic property.
- As \(\cos(\sqrt{x} + 1)\) depends on a non-periodic term, it is not periodic.
Therefore, the correct answers are (B) and (D).