解分式方程时,由于方程两边同时乘以的最简公分母未知是否为零,故所求出的解可能使分母为零,即为增根。据此可知,分式方程要有增根,未知数的取值必是使最简公分母为零。由此可判断有增根的分式方程其增根是多少,或在知道某一增根的条件下求出分式方程中其它字母的值。例1　若方 When the fractional equation is solved, since the simplest common denominator on the both sides of the equation is unknown at the same time whether it is zero or not, the solution obtained may cause the denominator to be zero, that is, to increase the root. Based on this, it can be seen that the fractional equation must be rooted, and the value of the unknown must be that the simplest common denominator is zero. From this we can determine the rooting of the fractional equation with increasing root, or find the value of other letters in the fractional equation under the condition of knowing an additional root. Example 1 If the party