7) The values that a can't take are the ones in options A and D.
8) Here the correct option is D, b can take any value.
Which value can't be taken by a?
Remember that a function is a relationship that maps elements from one set into elements from another set. Such that each element of the first set (the domain) can be mapped into only one element of the second set (the range).
This means that, for the table to represent a function, "a" can take a value that is already on the left side of the table.
We can see that 1 and -3 are already on the left side, so we can't select these two values, then the correct options are A and D.
For the second problem, notice that b is on the range. And we don't have any restrictions on the range, so b can be any value. Then here the correct option is D.
If you want to learn more about domains and ranges:
https://brainly.com/question/10197594
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