Question

Is {(1, 2); (2, 3); (3, 4); (4, 5)} a function?

Answer 1

Yes this is a function. The value of function is y = x+1;
because by putting the value of x and y in that equation. the equation is satisfied all the solutions.
Example.

By putting x = 1; we get y = 2;

when we put x = 2 we get y = 3;.
This kind of function called linear function. The standard form of this function is y = mx+c;
Here m is the slope and c is interesting point