Can someone tell me what the answer is to this and why it isn’t 3?

You are asking for the limit of a constant function.

The fact that is a constant function means that, for every input x you give to the function, the answer is always 3. So, for example,

And so on. The output doesn't depend on the input: it's always 3.

So, the limit you're asking for means: if my input approaches -3, what happens to the output? Well, we already know that the output doesn't depend on the input. So, the input can approach every value you want, but the answer will always be 3.

step-by-step explanation:

compare

step-by-step explanation:

this is not a question