Can someone teach me how to do these?

Question

anonymous · Answer

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mathstudent55 · Answer

The domain of a function is the set of numbers that can be used for x.
In this problem, the x variable is used in the log function.
For what values of x is log x defined?
For example:
Can you take the log of a positive number?
Can you take the log of zero?
Can you take the log of a negative number?
The domain is the set of numbers that is an answer of yes to any of the three questions above.

anonymous · Answer

So it could be positive... So C?

mathstudent55 · Answer

Correct. The log can be taken of only positive numbers. The answer is C.

anonymous · Answer

Is this correct?

mathstudent55 · Answer

No.
In this case, the 5 does not change the domain at all.
The domain is every value that can be used in the log function.
It's true that every value greater than or equal to 5 can be used for x, but so can every value greater than zero.

anonymous · Answer

So it's B.

mathstudent55 · Answer

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