By root, I think you mean square root. The square root of 2 is approx. 1.414. The square root of 9 = 3, so this goes exactly at 3 on the number line. Square root 2 will be less than 1/2 way between 1 and 2 on the number line.
Root 64 is 8, if by root you mean the square root. Then the problem become -square root 84(6+8) which is the - square root of 84(14) But square root of 84 is 2(square root of 21) so the final answer comes from -2(square root 21)x14 which is -28square root (21)
No, divisors are integers and square root are often not. So the square root of 4, for example, is 2 and yes 2 is a divisor of 4. But the square root of 5 is not a divisor of 5 because it is not an integer. So sometimes square root are divisors and more often they are not.