Answer:
The domain is 
Step-by-step explanation:
Given functions
and 
Subtract these two functions:

Plot these difference on the coordinate plane (see attached diagram). This function is defined for all vlues of x, so the domain is 
f(x) being even means
f(x) = f(-x)
So the zeros come in positive and negative pairs. If there are an odd number of intercepts like there are here, it's because one of them is x=0 which is its own negation.
Given zero x=6 we know x=-6 is also a zero.
So we know three zeros, and know the other two zeros are a positive and negative pair.
The only choice with (-6,0) and (0,0) is A.
Choice A
Answer:
x=5
Step-by-step explanation:
3.2x+4=20
Subtract 4 from both sides
3.2x=16
divide by 3.2
x=5
Answer:
The diameter is related because it helps find the circumference.