我们知道，解二元一次方程组的基本思路是消去一个未知数，转化成一元一次方程求解，泪元的方法是代入法和加减法．平时，我们都是循规蹈矩，按部就班地用代入法或加减法解一次方程组．实际上，代入法和加减法的作用不仅仅是消元，还能简化方程组，即使消元，也是灵活多变，技 We know that the basic idea of ​​solving a binary system of equations is to eliminate an unknown number and convert it into a one-dimensional first-order equation. The tear-teas method is substitution and addition and subtraction. In peacetime, we all follow the rules, step by step using substitution or addition and subtraction to solve a system of equations. In fact, substitutions and additions and subtractions are more than just elimination, but they can also simplify equations. Even if they are eliminated, they are flexible and technical.