在运用消元法解二元一次方程组时,若能注重整体思想的运用,可以提高解题速度和准确率.一、代入消元法中的整体思想例1解方程组{3x+5y=21,①4x+15y=53.②分析:方程组中y的系数成倍数关系,可考虑把①变形为5y=21-3x,整体代入②,先求出x的值,再求出y的值.解:由①,得5y=21-3x.③把③代入②,得4x+3(21-3x)=53.解得x=2把x=2代入③,得5y=21-6,解得y=3. In the use of elimination element method to solve a linear equation, if we can focus on the use of the overall idea, you can improve the speed and accuracy of solving problems .And into the elimination of the total ideas in the case of Example 1 solution equation group {3x + 5y = 21, ① 4x + 15y = 53. ② Analysis: coefficient of y in the system of multiple factor relationship can be considered ① deformation of 5y = 21-3x, the overall substitution ②, first find the value of x, and then find the value of y Solution: From ①, get 5y = 21-3x.③ Put ③ into ② and get 4x + 3 (21-3x) = 53. Solve x = 2 Substitute x = 2 into ③, get 5y = 21-6, Solve y = 3.