关于x的方程(k+1)x^2+(2k-1)x+k+3=0有实数根
△=(2k-1)²-4(k+1)(k+3)>=0
4k²-4k+1-4(k²+4k+3)>=0
4k²-4k+1-4k²-16k-12>=0
-20k-11>=0
解得k小于等于11/20
关于x的方程(k+1)x^2+(2k-1)x+k+3=0有实数根
△=(2k-1)²-4(k+1)(k+3)>=0
4k²-4k+1-4(k²+4k+3)>=0
4k²-4k+1-4k²-16k-12>=0
-20k-11>=0
解得k小于等于11/20