Question

这个题如何求偏导对 sqr[(x0-x)^2+(y0-y)^2+(z0-z)^2]分别对x,y,z求偏导……我不知道有根

Answer 1

f=sqrt[(x0-x)^2+(y0-y)^2+(z0-z)^2]

df/dx=1/2*{1/sqrt[(x0-x)^2+(y0-y)^2+(z0-z)^2]}*2(x0-x)*-1

=(x-x0)/sqrt[(x0-x)^2+(y0-y)^2+(z0-z)^2]

同理

df/dy=(y-y0)/sqrt[(x0-x)^2+(y0-y)^2+(z0-z)^2]

df/dz=(z-z0)/sqrt[(x0-x)^2+(y0-y)^2+(z0-z)^2]