Guangzhou senior high school entrance examination 1 D X cannot be 1 and x is greater than or equal to 0.

Qujing senior high school entrance examination 2 3 or -2 does not explain.

Deyang senior high school entrance examination 3 forgives the poor. . .

Liupanshui senior high school entrance examination 4 m is less than or equal to 9. If there is a root, it must be the square of b MINUS 4 times, and ac is greater than or equal to zero.

Example 2 chooses D k=3, m=2 and n=5.