现在高中的导数题不再只限于高中所学内容,所用方法,特别是一些证明题,容易与大学中极限、微积分中的一些基本定理、不等式等内容联系起来。在某些函数的变化规律中,单元变量略显不足,所以常常会引入多元变量。这就要求我们在复杂的多元变量中理清思路。那么这时,主元法就成了化繁为简,快速解决问题的一种利器。 Now the derivative problem of high school is no longer limited to what is taught in high school. The methods used, especially some proving items, are easily related to the limits in universities, some basic theorems in calculus, and inequalities. In the change law of some functions, the unit variables are slightly insufficient, so multiple variables are often introduced. This requires us to sort out our ideas in complex, multiple variables. At this time, the principal element method has become a powerful weapon for simplifying and simplifying problems.