[m]\frac{ ∂ z}{ ∂ x}=(x\cdot sin(x+y))`_{x}=1\cdot sin(x+y)+x\cdot cos(x+y)[/m]
[m]\frac{ ∂ z}{ ∂ y}=(x\cdot sin(x+y))`_{y}=x\cdot cos(x+y)[/m]
[m] \frac{dx}{dt}=(\frac{1}{t^3})`_{t}=(t^{-3})`_{t}=-3t^{-4}=-\frac{3}{t^4}[/m]
[m] \frac{dy}{dt}=((t-1)^2)`_{t}=2\cdot (t-1)[/m]
О т в е т.
[m]\frac{dz}{dt}= (sin(x+y)+x\cdot cos(x+y))\cdot( -\frac{3}{t^4})+x\cdot cos(x+y)\cdot 2\cdot (t-1)[/m]