Question

如图,双曲线y=k/x与直线y=xm交于点A,B,AC⊥x轴于C,BC交y轴于D,且S△OCD=2,求k的值

用初二反比例函数知识

Answer 1

 

 

 

那步不明白可以追问

Answer 2

按图，k>0, m > 0
k/x = mx, x² = k/mk, x = ±√(k/m), y = ±√(km)

A(√(k/m), √(km)), B(-√(k/m), -√(km))
C(√(k/m), 0)
BC的方程: (y - 0)/[-√(km) - 0] = [x - √(k/m)]/[-√(k/m) - √(k/m)]
x = 0, y = -√(km)/2
D(0, -√(km)/2)
S△OCD = (1/2)OD*OC
= (1/2)[√(km)/2]√(k/m)
= k/4 = 2
k = 8

Answer 3

这个是真忘了怎么做了 得复习一下了