若方程kx^2-(m-1)x+k=0有实数解,求实数K的取值范围?

题目

若方程kx^2-(m-1)x+k=0有实数解,求实数K的取值范围?

答案

kx^2-(k-1)x+k=0有实数解
△=(k-1)^2-4k^2≥0
(k-1+2k)(k-1-2k)≥0
(3k-1)(-k-1)≥0
(3k-1)(k+1)≤0
-1≤k≤1/3