初二上学期分式加减,如下图↓

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初二上学期分式加减,如下图↓

初二上学期分式加减,如下图↓
初二上学期分式加减,
如下图↓

初二上学期分式加减,如下图↓
原式=[(a+1)/a(a-1)-4/(a+1)(a-1)]÷[(a-1)(a+3)/(a+3)]
={[(a+1)²-4a]/[a(a-1)(a+1)]}÷(a-1)
={(a²+2a+1-4a)/[a(a-1)(a+1)]}÷(a-1)
=(a²-2a+1)/[a(a-1)²(a+1)]
=(a-1)²/[(a-1)²(a²+a)]
=1/(a²+a)

括号里面先通分,分母变为a(a-1)(a+1)
分子为(a+1)(a+1),-4a(a+1)(a-1)
则得分母为a(a+1)(a-1)
分子为-3(a+1)(a-1)
则得为-a/3
括号外面分子化简为(a-1)(a+3)
分式化简为(a-1)
则-a/3除以(a-1)
得-a/3乘以(a-1)/1
得-a(a-1)/3
得a-a.a/3