分式的加减运算分为同分母的分式相加减和异分母的分式相加减．同分母的分式相加减的法则是：分母不变，把分子相加减．异分母的分式相加减的法则是：先通分，变为同分母的分式，然后再加减．以上是从一般性原则上讲的，但对一些具体分式的加减运算，若用上述的一般解法，则运? Fractional additions and subtractions are divided into fractions of the same denominator, additions and subtractions, and fractional additions of different denominators. The rule of addition and subtraction with the fractions of the denominator is that the denominator is unchanged and the numerator is added or subtracted. The principle of addition and subtraction of the fractions of the different denominators is: pass the points first, become fractions of the same denominator, and then add and subtract. The above is based on the general principle, but the addition and subtraction of some specific fractions will be performed if the above general solution is used.