Calculate the value of the mathematical function y = f (x). It is possible to assign to x any integer, rational number, irrational number. For example, you can assign square root 2 to x. It is not necessary to fix it to decimal. The calculation result is output in the form of a fraction using square root. It is exactly the same as math calculations. You can also convert the result to decimal. Calculate the values ​​of f (α) and f (β) for two kinds of values, x = α and x = β, and f (α) + f (β), f (α) - f ), F (α) * f (β), f (α) / f (β) can also be calculated.