A:2,5
B:2,2
C:5,7
D:2,7
— We often use QQ to chat with friends on the Internet.
— Really? Will you please show me it?
He is a ____.
已知关于x的一元二次方程x2-6x+k+1=0的两个实数根是x1,x2,且x12+x22=24,则k的值是( )