MathDB
y=(x^2-2x+1)/(x^2-2x+2), image of y

Source: Bulgaria 1962 P1

June 24, 2021
algebra

Problem Statement

It is given the expression y=x22x+1x22x+2y=\frac{x^2-2x+1}{x^2-2x+2}, where xx is a variable. Prove that:
(a) if x1x_1 and x2x_2 are two values of xx, the y1y_1 and y2y_2 are the respective values of yy only if x1<x2x_1<x_2, y1<y2y_1<y_2; (b) when xx is varying yy attains all possible values for which 0y<10\le y<1.