Question

数学解答 要过程

急

Answer 1

x+y=4
x-y=2√3
xy=2²-(√3)²=1

(x+y)/(x-y)-(x-y)/(x+y)
=[(x+y)²-(x-y)²]/(x+y)(x-y)
=4xy/(x+y)(x-y)
=4/(4×2√3)
=√3/6

1/x²+1/y²
=(x²+y²)/x²y²
=[(x+y)²-2xy]/(xy)²
=(4²-2)/1²
=14

你两个括号中间是什么符号
如果是乘号
则原式=√3/6×14=7√3/3

Answer 2

d
|x|<=2,|y|<=2
-2<=x<=2,
-2<=y<=2
所以就是乙x=2,x=-2,y=2,y=-2围城的正方形
面积是16

e
则是单位圆
所以面积是π

所以概率=π/16