Answer:
2√17
Explanation:
Start with thinking of factors of 68. Those are:
1, 2, 4, 17, 34, 68
Within this set of numbers, are there any available that are the square of a number? The 4 does! 68 / 4 = 17
So we can change √68 to be √(4 x 17)
Which is the same as √4 x √17
Which can be simplified to 2 x √17
Or 2√17