利用一元二次方程解应用题时,由于所列方程的根有两个,常会遇到要舍根的问题.虽然都是方程的根,但不一定都符合题意,同学们要在仔细审题的基础上认真对待,不要一看到正数根就保留,一看到负数根就舍去,要根据问题的实际意义进行合理的取舍.一、正增长率问题中出现负增长率,应舍去例1雅安地震牵动着全国人民的心,某单位 Use of a quadratic equation to solve the problem, due to the root of the equation has two, often encounter the problem of root needs to be rooted. Although they are root of the equation, but not necessarily in line with the questions, students should be carefully examined On the basis of serious treatment, do not see a positive number on the reservation, one saw the negative number to give up, according to the actual significance of the problem to make a reasonable choice .A positive growth rate in the negative growth rate should be discarded Example 1 The Ya’an earthquake affected the hearts and minds of people across the country