第1个回答 2011-01-29
解:原式=a/(a²-1)+(3a+1)/(a²-1)-(2a+3)/(a²-1)
=(a+3a+1-2a-3)/(a²-1)
=2(a-1)/(a²-1)
=2/(a+1)
第2个回答 2011-01-29
原式=a/(a^2-1)+(3a+1)/(a^2-1)-(2a+3)/(a^2-1)
=(a+3a+1-2a-3)/(a^2-1)
=(2a-2)/(a^2-1)
=2/(a+1)
第3个回答 2011-01-29
原式=a/(a^2-1)+(3a+1)/(a^2-1)-(2a+3)/(a^2-1)
=(a+3a+1-2a-3)/(a^2-1)
=(2a-2)/(a^2-1)
=2/(a+1)