题目内容
已知函数y=

【答案】分析:先找出两条渐近线,一条为x=0,一条为y=
x,由此可知此双曲线的对称轴方程,求出此对称轴与双曲线的交点,即可求出最小距离.
解答:
解:函数y=
x-
的导数为y′=
+
>
,所以函数的渐近线方程为:x=0与y=
x,
两条渐近线的角的平分线与x轴所成的倾斜角为-15°,其方程为:y=tan(-15°)x=(
)x,
它与函数y=
x-
的交点为:(
,-
),(-
,
),
PQ两点的最短距离为:2
-2.
故答案为:2
-2.
点评:本题考查双曲线的基本性质,利用函数的导数求出函数的斜率范围,推出双曲线的渐近线,求出双曲线的对称轴方程是解题的关键.

解答:







两条渐近线的角的平分线与x轴所成的倾斜角为-15°,其方程为:y=tan(-15°)x=(

它与函数y=






PQ两点的最短距离为:2

故答案为:2

点评:本题考查双曲线的基本性质,利用函数的导数求出函数的斜率范围,推出双曲线的渐近线,求出双曲线的对称轴方程是解题的关键.

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