Question

Please help me, If you do not know do not answer

Answer 1

Answers:

1. Function
2. Function
3. Not a function
4. Not a function

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Explanation:

1. Relation 1 is a function because any input item in the domain leads to exactly one and only one output item in the range. If we had say 2 arrows coming from "chair", and pointing to two different outputs, then we wouldn't have a function. It's perfectly possible to use words in place of numbers when talking about functions. All that matters is that we have one input map to exactly one output.
2. Relation 2 is a function for similar reasoning as relation 1. It's possible to have an output repeated and still have a function.
3. Relation 3 is not a function. Why not? Because of the points (j,v) and (j,t). The input j leads to more than output (v and t at the same time). A similar issue happens with the input 's' also.
4. Relation 4 is also not a function. The repeated input this time is -5 which maps to the outputs z and 'a' at the same time.

Answer 2

1 and 2 are functions.

3 and 4 are not.

Each different x can only have 1 y value.