Answer with Step-by-step explanation:
Let F be a field .Suppose
and 
We have to prove that a has unique multiplicative inverse.
Suppose a has two inverses b and c
Then,
where 1 =Multiplicative identity

(cancel a on both sides)
Hence, a has unique multiplicative inverse.
Answer:
Single Blind (option 1)
Step-by-step explanation:
The subjects don't know which cream they have but the technicians do.
If the subject knows which cream they have then they can be influenced by the placebo effect. If they don't know but the technicians do then the technicians will be able to look at unbiased responses from the subjects and tell if it works or not. If the technicians don't know which cream each subject has then they won't be able to learn anything from the responses. The technicians need to know which cream each subject has and the subjects can't know which cream they had.
From the given table, the points can be written as : (6,7.55) , (12,7.85), (18, 8.15) and (24, 8.45)
Slope 
m = 
m = 0.05
slope intercept form of line = 
We plug m = 0.05, x = 6 and y = 7.55 and find c.

c= 7.25
Required equation:
... Answer
18miles/6mph = 3hrs
3 hours