x1+x2=-(k+2)/2
x1x2=-k/2
x1x2(x1+x2)=3/4
[-(k+2)/2][-k/2]=3/4
k²+2k=3
k²+2k-3=0
(k+3)(k-1)=0
k=-3,k=1
有解判别式大于等于0
(k+2)²+8k>=0
k=-3不成立
所以k=1
x1+x2=-(k+2)/2
x1x2=-k/2
x1x2(x1+x2)=3/4
[-(k+2)/2][-k/2]=3/4
k²+2k=3
k²+2k-3=0
(k+3)(k-1)=0
k=-3,k=1
有解判别式大于等于0
(k+2)²+8k>=0
k=-3不成立
所以k=1