a^3+3a^2+a=0 5a^2/a^4+8a^2+1=?

问题描述:

a^3+3a^2+a=0 5a^2/a^4+8a^2+1=?

a^3+3a^2+a=0,得:a=0或a^2+3a+1=0,即a^2=-1-3a.所以:5a^2/(a^4+8a^2+1)= 0 或1/3.0很容易理解,下面是1/3的推导过程:把a^2=-1-3a带入式子:5a^2/(a^4+8a^2+1)=(-5-15a)/(a^4+8a^2+1)= (-5-15a)/((-5...