学习了分式加减运算法则，同学们对法则的正向运用比较得心应手，而对法则的逆用却不习惯．其实有许多问题，逆用分式加减运算法则，能得到巧妙的解法．一、用于化简例！化简：解原式二、用于求值．求下式的值：（1994年初一《祖冲之杯》数学邀请客试题）解”．，由非负数的性 Learned the fractional addition and subtraction algorithm, the students are more comfortable with the positive use of the law, and the inverse of the law is not used. In fact, there are many problems. Inversely using fractional addition and subtraction algorithms, you can get clever solutions. First, for simplified examples! Simplification: solution of the original two, for the evaluation. Find the value of the following formula: (In early 1994, “Zu Chong Cup” mathematics invited guest questions) solution". By non-negative sex