It is proved that f (x) = √ (x ^ + 1) - x is a decreasing function in the domain of definition

It is proved that f (x) = √ (x ^ + 1) - x is a decreasing function in the domain of definition

Let X1 and X2 be any two values on the interval (negative infinity, positive infinity) and be x1x1
So x2-x1 > 0, and the root sign (x2 ^ 2 + 1) + root sign (x1 ^ 2 + 1) > 0
And any x belongs to real number, has root sign (x2 ^ 2 + 1) > square of root sign x = absolute value x > = X
So x-radical (x1 ^ 2 + 1)