Question

xy方程组求k的取值范围

数学题方程组xy=6 xy=-6
求k的取值范围 答案为k大于等于6或k小于等于-6
x+y=k xy=6

Answer 1

xy=6
x+y=k
(k-y)y=6
y^2-ky+6=0
(y-k/2)^2=k^2/4-6>=0
K^2>=24
k>=2√6或k