Answer: It is B)
Step-by-step explanation: It was 8.66 something and that rounded to the nearest tenth is 8.7
Answer: 
Step-by-step explanation:
Given the following expression shown in the picture:

You need to use a process called "Ratinalization".
By definition, using Rationalization you can rewrite the expression in its simplest form so there is not Radicals in its denominator.
Then, in order to simplify the expression, you can follow the following steps:
<em>Step 1</em>. You need to multiply the numerator and the denominator of the fraction by
, which is the conjugate of the denominator
.
<em>Step 2</em>. Then you must apply the Distributive property in the numerator.
<em>Step 3</em>. You must apply the following property in the denominator:
Therefore, applying the procedure shown above, you get:

<em>Step 4</em>. You can observe that the expression can be simplified even more. Since:

You get:

Answer:

Step-by-step explanation:
So we have the equation:

First, let's distribute the negative:

Combine like terms:

Subtract or add:

Subtract 6 from both sides:

Divide both sides by 3:

And we're done!
The diameter is equal to 12.