问题
填空题
若k为整数，关于x的一元二次方程（k-1）x2-2（k+1）x+k+5=0有实数根，则整数k的最大值为______．
答案
∵方程有实数根，
∴△=4（k+1）2-4（k-1）（k+5）≥0，且k-1≠0，
解得：k≤3且k≠1，
故整数k的最大值为3．
故本题答案为：3
搜题请搜索小程序“爱下问搜题”
若k为整数，关于x的一元二次方程（k-1）x2-2（k+1）x+k+5=0有实数根，则整数k的最大值为______．
∵方程有实数根，
∴△=4（k+1）2-4（k-1）（k+5）≥0，且k-1≠0，
解得：k≤3且k≠1，
故整数k的最大值为3．
故本题答案为：3
Passage Four
Under what circumstance can we tell an accident is probably caused by sleepiness
A．If traffic is light and vehicles are well-spaced on the road.
B．When there is only one car involved in the accident.
C．If there is no skid marks or other signs of braking on the road.
D．All of the above.