Let's call the two number and . Since we know that the difference between them is , if we assume to be the largest we have
Their product is , which we can write as
This is the equation of a parabola, since it is a polynomial of degree . To find its minimum, simply derive it and set the derivative to zero: using the power rule
we have the following derivative:
Now that we have found one variable, we can substitute its value in the formula that related it to the other variable: