Therefore, ∂ z ∂ x = 3 {\displaystyle {\frac {\partial z}{\partial x}}=3} at the point ( 1 , 1 ) {\displaystyle (1,1)} .
Tedy můžeme položit, že ∂ z ∂ x = 3 {\displaystyle {\frac {\partial z}{\partial x}}=3} V bodě (1, 1, 3).