Which of the following gives an example of a set that is closed under addition?

The sum of an odd number and an odd number
The sum of a multiple of 3 and a multiple of 3
The sum of a prime number and a prime number
None of these are an example of the closure property

Question

Which of the following gives an example of a set that is closed under addition?
 	
	The sum of an odd number and an odd number
	The sum of a multiple of 3 and a multiple of 3
	The sum of a prime number and a prime number
	None of these are an example of the closure property

anonymous · Answer

there the ones on the bottom of the question

anonymous · Answer

can you help me

anonymous · Answer

The formula to find the surface area of a sphere is to take the radius of the sphere and square 
it and multiply that amount by pi and then multiply that by 4. This is written algebraically as 
S=4πr
2
, where S is the surface area, r is the radius, and the value of π is 3.14. Rewrite the 
equation to solve for the radius of the sphere if you know the sphere’s surface area. Then 
estimate the radius of a sphere given a surface area of 500 meters2
.