According to the relationship between function and equation

(x-a)(x-b)=0？ The intersection of the function and the x axis is (a, 0)(b, 0).

According to the property of quadratic function, when y= 1, (that is, (x-a)(x-b)= 1).

The intersection of functions is (x 1, 1)(x2, 1), as shown in the figure.

According to the image, x1< a <; b & ltx2。