解方程组时 ,常用的方法是代入法、加减法和因式分解法 ;有时根据系数和常数的特点 ,对方程组进行处理 ,也有其独到之处 ,其中的特殊消元法———“消常数法” ,频繁出现在各级各类竞赛中 ,应用很多 .例 1　 ( 1999年武汉市竞赛题 )设ｘ、ｙ为实数 ,且满足(ｘ -1) 3 + 1998(ｘ When solving equations, the commonly used methods are substitution method, addition and subtraction, and factorization; sometimes the equations are treated according to the characteristics of coefficients and constants, and there are also unique features, among which the special elimination method— The “constant-constant method” is frequently used in various types of competitions at various levels and has many applications. Example 1 (1999 Wuhan City Competition Title) Let x and y be real numbers and meet (x -1) 3 + 1998 (x