计算:3/(2a+4)-6/(4-a²)+9/(2a-4)

问题描述:

计算:3/(2a+4)-6/(4-a²)+9/(2a-4)

=[3*(2a-4)+9*(2a+4)]/(2a+4)(2a-4)+6/(a2-4)
=(6a+6)/(a2-4)+6/(a2-4)
=6(a+2)/(a+2)(a-2)
=6/(a-2)