An oracle function $f(x,y)$ is presented below. If you enter a point $(x,y)$ on the left then push the "--f-->" button the oracle will tell you the value $f(x,y)$.

Use the oracle to compute several values $f(x,y)$ then estimate the partial derivative $f_x(1.2,1.9)$ of the function at $(1.2,1.9)$, using the Newton quotient definition.

$f_x (1.2,1.9) \approx$

Remember the technique for finding partial derivatives from tables? This is the same thing. For credit your answer must be within 1% of the correct value, so use lots of decimal places. Also remember that you can cut and paste the output from the oracle function.