{1+4/a²-4}÷a/a-2{}是大括号
问题描述:
{1+4/a²-4}÷a/a-2
{}是大括号
答
{1+4/a²-4}÷a/a-2
=(a²-4+4)/(a²-4)÷a/(a-2)
=a²/(a-2)(a+2)×(a-2)/a
=a/(a+2)