Question: what is the math equation for function?
Answer: For essence 'h (a) = x*a + b', where 'x' is the slope of the function and 'b' is the Y-axis intersection, or what you call is as a "Y intersect". ( Remember 'b' can either be positive or negative) A function is nothing but a number "operator" it takes some numbers & variables, fiddles with it and gives only one output.