when u=2 ,v=3 ,w=4 then p=14 q=11 r=10
∵∂N/∂p=1/(p+r)-(p+q)/(p+r)^2,
∂N/∂q=1/(p+r),
∂N/∂r=-(p+q)/(p+r)^2
∂p/∂u=1 ∂q/∂u=w ∂r/∂u=v
∂p/∂v=w ∂q/∂v=1 ∂r/∂v=u
∂p/∂w=v ∂q/∂w=u ∂r/∂w=1
∴when u=2 ,v=3 ,w=4 and p=14 q=11 r=10
∂N/∂p=-1/576 ∂N/∂q=1/24 ∂N/∂r=-25/576
∂p/∂u=1 ∂q/∂u=4 ∂r/∂u=3
∂p/∂v=4 ∂q/∂v=1 ∂r/∂v=2
∂p/∂w=3 ∂q/∂w=2 ∂r/∂w=1
there for
∂N/∂u=(∂N/∂p)(∂p/∂u)+(∂N/∂q)(∂q/∂u)+(∂N/∂r)(∂r/∂u)=(-1/576)+(1/24)4+(-25/576)3=5/144
∂N/∂v=(∂N/∂p)(∂p/∂v)+(∂N/∂q)(∂q/∂v)+(∂N/∂r)(∂r/∂v)=(-1/576)4+(1/24)+(-25/5762=-15/288
∂N/∂w=(∂N/∂p)(∂p/∂w)+(∂N/∂q)(∂q/∂w)+(∂N/∂r)(∂r/∂w)=(-1/576)3+(1/24)2+(-25/576)=5/144