Rounded to two decimal places, the square root of 34 is 5.83. It is not possible to simplify the radical ?34 because the number 34 does not have any perfect square factors.
Sometimes one can simplify a radical expression rather than resorting to writing it as a rounded decimal, even if the number under the square root is not a perfect square. For example, ?32 can also be written as 4?2, because ?32 = ?(16*2) = ?16 * ?2 = 4*?2. This works because 32 has 16 as a factor, and 16 is a perfect square. The factors of 34 are 1, 2, 17 and 34, none of which are perfect squares, so ?34 does not simplify any further.