1)设v=kw^2
将(3,54000)代入上式,
k=6000
所以v=6000w^2
2)设原钻石重量为4w
原来价值v=6000*16w^2=96000w^2
切割后价值v=6000*w^2+6000*9w^2=60000w^2
损失的百分率=(96000-60000)/(96000)=37.5%
3)设钻石重量w=x+y.即切割成x,y两部分.
v=6000w^2=6000(x+y)^2
v'=6000(x^2+y^2)
价值损失的百分率=(v-v')/v=2xy/(x+y)^2=1/[x/(2y)+1+y/(2x)]