对于二次函数解析式中字母的求值问题,我们经常会遇到,它的求解与求二次函数的解析式不同之处表现在:(1)求解析式中字母的值通常要比求解析式在解题步骤上少一步(即少写“故所求的解析式为……”);(2)求解析式的题目,一般不会给出解析式,只给出几个需要的条件,解析式通常需要我们根据条件灵活设定;(3)求字母 We often encounter problems in the evaluation of letters in the quadratic function analysis. The differences between the solution of the letter and the analytical solution of the quadratic function are as follows: (1) Analytic formula in the problem-solving steps on the less one-step (that is, write less “so the analytical formula required for ... ”); (2) analytical expression of the problem, generally not given analytic, only to give a few Need conditions, analytical style usually require us to set the conditions of flexibility; (3) seeking letters