The answer to your question is D) √5x/5x.
I hoped this helped!
It is between 3.1 and 3.17 or 3.2 if you want it by hundredths.
This is because 3.16 is 3.1600000 and many more zeros but 3.16227766 is slightly over that so it would be between 3.1 and 3.17.
Answer:
Option A. is the right choice.
Step-by-step explanation:

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Substitute 3x+1 for x. Then solve from there
Diameter- Is two times the radius. Circumference is the distance around the edge of the circle.
Radius- A line from the center of a circle to a point on the circle.
Hope this helped.