1. You need to multiply the denominator by something that will make the content of the radical be a square—so that when you take the square root, you get something rational. Easiest and best is to multiply by √6. Of course, you must multiply the numerator by the same thing. Then simplify.

2. Identify the squares under the radical and remove them.

You can group first two conjunctions and second two:

.
In first brackets you have common

and in second brackets common is 5:

.
What you have written down is correct, x=-3
Answer:
0.0537
Step-by-step explanation:
This follows a binomial distribution with : n
Number of trials 'N' = 12 ; Probability of success (difference between speakers) 'p' = 1/2 or 0.5 ; Probability of failure (no difference b/w speakers) = 1/2 or 0.5 ; No of success 'r' = 3
P (X = 3) = 
= 12C3 (0.5)^3 (0.5)^9
0.0537