## Calculus 8th Edition

$\approx 12.2$; $\approx 16.8$ and $\approx 23.25$
The rate of change in the x-direction is given as: $f_x(3,2)=\dfrac{22.4-10.2}{3.5-2.5} \approx 12.2$ and $f_x(3,2.2)=\dfrac{26.1-9.3}{3.5-2.5} \approx 16.8$ Also, $f_{xy}(3,2)=\dfrac{(26.1-9.3)-(20.0-12.5)}{2.2-1.8} \approx 23.25$