这一次的重难点笔记，我们将注意力放在较为基础，但却又非常重要的二次方程的解法上。在同学们八年级和九年级的学习中，我们已经逐渐了解和掌握了因式分解法求二次方程解的一般步骤，讲方程分解为(x-a)(x-b)=0的形式，然后发现x可以等于a或者b。
但是，随着同学们的习题量增多，大家发现，我们的数学中存在着很大一部分的二次方程，它们并不可以用因式分解法找出答案，因为他们的解往往以根式(无理数)的形式存在，所以，这就需要我们开发新的方法去求解更加普遍和一般的二次函数。
This time, we will focus on the more basic but very important solution of quadratic equations. In the eighth and ninth grades of the students, we have gradually understood and mastered the general steps to find the solution of a quadratic equation by factoring, decomposing the equation into the form of (x-a)(x-b)=0, and then finding x Can be equal to a or b.
However, with the increase in the number of exercises for students, we found that there are a large part of quadratic equations in our mathematics, and they cannot be solved by factoring, and their solutions often appear in the form of irrational numbers . Therefore, this requires us to develop new methods to solve more general quadratic functions.
用完成平方的方法解一元二次方程可归纳成如下步骤：
（1）移项将二次项、一次项保留在方程的左边，把常数“孤立”在方程的右边
（2）化二次项系数为1两边同时除以二次项的系数
（3）配方两边同时加上一次项系数一半的平方
（4）两边开平方
（5）写出方程的解，解线性方程
具体例题如下：
Solving the quadratic equation in one variable by the method of completing the square can be summarized into the following steps:
(1) Shifting the term keeps the quadratic term and the primary term on the left side of the equation, and "isolates" the constant on the right side of the equation
(2) Convert the coefficient of the quadratic term to 1 and divide both sides by the coefficient of the quadratic term
(3) Add the square of half of the coefficient of the first-order term on both sides of the formula at the same time
(4) Square root on both sides
(5) Write the solution of the equation and solve the linear equation
二次方程作为数学的基础，希望大家要勤联系，少犯错。我也希望以上的总结能够对大家求解二次方程有帮助。
