有这样一类问题:已知一个含参方程(函数),它的根(零点)在区间(a,b)上,求其中参数的取值范围.换言之,求出了参数的取值范围,即可把方程的根(函数的零点)牢牢地锁在区间(a,b)上,故我们把这类问题称为“锁根(零点)问题”.下面就来探讨一下如何把方程的根(函数的零点)锁住.一、用f(a).f(b)<0锁根已知函数y=f(x)在区间[a,b]上是单调函数,且它的图 There is such a problem: we know a parameter-containing equation (function) whose root (zero point) is in the interval (a, b) and find the range of the parameter in other words, We can lock the root of the equation (the zero of the function) in the interval (a, b), so we call this kind of problem “root-locking problem” The root of the equation (the zero point of the function) is locked. First, the known function y = f (x) with f (a) .f (b) <0 is a monotonic function in the interval [a, b] The picture