数学题，要过程已知关于x的一元二次方程x?-(2k+1)x+k?+2k=0有两个实数根x1，x2.

b?-4ac

=(2k+1)?-4(k?+2k)

=4k?+4k+1-4k?-8k

=-4k+1

∵有两个实数根

∴-4k+1>=0

∴k<=1/4

2、根据根与系数关系得

x1x2-x1?-x2?=-x1?-2x1x2-x2?+3x1x2=-(x1+x2)?+3x1x2=-(2k+1)?+3(k?+2k)

=-4k?-4k-1+3k?+6k

=-k?+2k-1

=-(k-1)?

∵x1*x2-x1?-x2?≥0

∴ -(k-1)?>=0

∴k=1

又∵k<=1/4

∴不存在k值