数学问题中,往往有多个变量,如果选择其中某个变量为主变量,将其它变量看作常量,则可为解决这类问题打开通道.这种以某个变量为主变量去分析解决问题的方法称为“主元法”.一、利用主元法解特殊方程或求值例1已知关于x,y的方程x2-4x+y2-2y+5=0,求x,y的值.解将方程x2-4x+y2-2y+5=0看 Mathematical problems, there are often multiple variables, if you choose one of the variables as the main variable, the other variables as a constant, you can open the channel to solve such problems.This variable to the main variables to analyze and solve the problem Of the method known as the “principal element method.” First, the use of principal component method to solve special equations or evaluation Example 1 Known on x, y equation x2-4x + y2-2y +5 = 0, find x, y The solution to the equation x2-4x + y2-2y + 5 = 0 look