Answer:
Step-by-step explanation:
3(a+3)-6=21
<=>3a+9-6=21
<=>3a+3=21
<=>3a=18
<=>a=6
The probability of an event is given by the number of favorable outcomes divided by the total number of outcomes. Here the event is the alarm clock running out of power. There are 24 hours during which the power can go out. You are asleep during 8 of these. A "favorable" outcome in this case is the power going out while you are sleeping -- that is, during one of those 8 hours. This makes the probability that the power goes out while you are sleeping 8/24.
To take out terms outside the radical we need to divide the power of the term by the index of the radical; the quotient will be the power of the term outside the radical, and the remainder will be the power of the term inside the radical.
First, lets factor 8:
Now we can divide the power of the term, 3, by the index of the radical 2:

= 1 with a remainder of 1
Next, lets do the same for our second term

:

= 3 with a remainder of 1
Again, lets do the same for our third term

:

with no remainder, so this term will come out completely.
Finally, lets take our terms out of the radical:

We can conclude that the correct answer is the third one.