Answer:
1. Function
2. Not a function
3. Function
4. Not a function
Step-by-step explanation:
A function just means that for each input it outputs only 1 output. This output isn't necessarily unique. So for example if you're just given: f(2) = 3 and f(1) = 3, this is a function since each input only outputs 1 value, even though the output isn't unique, but if you're given: f(3) = 2, f(2) = 1, f(3) = 3. that's not a function since f(3) outputs both 2 and 3.
Anyways now that you hopefully understand this, let's look at each image.
Relation 1: (Function)
So for each input (the domain) it's only pointing to one output (range), even if multiple input (the domain) are pointing to the same output (the range), it's still a function.
Relation 2: (Not a function)
This is not a function, since if you look at the input 7 (the range), you'll see it outputs two things (range). It outputs -6 and -7. So this is not a function
Relation 3: (Function)
This is a function since each x-value (input) has only one y-value (output). So it's a function
Relation 4: (Not a functio)
This is not a function, since there are multiply coordinates with the same x-coordinate (input) and different y-coordinates (output). The x-coordinate 2 has the output b, y, and m, and since no value is given for these variables, it can be assumed they're different values, thus it's not a function.
