y=x^2-(k-1)x-3k-2
与x轴交于A(a,0)B(b,0)
则a,b是方程x^2-(k-1)x-3k-2=0的两个跟
所以a+b=k-1
ab=-3k-2
且判别式大于0
(k-1)^2-4(-3k-2)>0
k^2+10k+9>0
(k+1)(k+9)>0
k>-1,k-1,k
y=x^2-(k-1)x-3k-2
与x轴交于A(a,0)B(b,0)
则a,b是方程x^2-(k-1)x-3k-2=0的两个跟
所以a+b=k-1
ab=-3k-2
且判别式大于0
(k-1)^2-4(-3k-2)>0
k^2+10k+9>0
(k+1)(k+9)>0
k>-1,k-1,k