(1)
方程有兩個不等的實數(shù)根,則判別式大于0且k≠0
Δ=(k+1)²-4k(k/4)>0 且k≠0
k²+2k+1-k²>0 且k≠0
k>-1/2 且k≠0
實數(shù)k的取值范圍是 -1/2
(2)
設(shè)方程的兩根是a,b,由韋達定理得
a+b=-(k+1)/k,ab=(k/4)/k=1/4
兩根的倒數(shù)和
=1/a+1/b
=(a+b)/(ab)
=[-(k+1)/k]/(1/4)
=-4(k+1)/k
=0
所以k+1=0,k=-1<-1/2
所以不存在實數(shù)k,使得方程的兩根倒數(shù)和為0