1) order root number1-2x = t (t > =0, x is less than or equal to 1/2)

Then Y=-1/2(t- 1) squared+1.

So this is a downward opening, and the symmetry axis is t= 1, so the maximum value is obtained when t= 1, at this time, X=0, Y= 1.

2) radical number x = t(t >；; =0，X & gt=0)

Then Y=X squared -X, and the formula is, Y=(T- 1/2) squared-1/4.

So this is open, and the symmetry axis is T= 1/2, so the minimum value is obtained when T= 1/2, and at this time, X= 1/4 and Y=- 1/4.

This kind of topic is to set everything under the root sign as t, pay attention to the definition domain of x and t >; =0, and then calculate x (that is, use t to represent x), so that a new equation without root sign can be obtained, which can be easily solved by combining formulas and graphs. Please note, however, that if the topic is "Y is the largest when taking X", you must take the obtained t into the substitution equation to find X..