We all are familiar with (x,y) coordinate plane where some lines or curves are drawn. These curves are drawn or made up using some (x,y) points. These values of (x,y) points satisfy the equation of curves.
The equation of x and y variables is called a Relationship. Now, a Function is a "special relationship of x and y variables" where each input x has a single answer for output y.
In other words, we can say any relation y=f(x) would be a "Function" if and only if each value of x input give us a unique value of y output from the equation. No two values of y can be output of same x-value input.
For example:- y = f(x) = 2x is a Function because each value of x would give unique answer for y. x=4 gives y=8.
Another example is:- y = f(x) = √x is "not a function" because one-value of x would give two answers of y. x=4 gives y= -2 and y=2.
