Find the partial derivative ∂x
∂z
​
for the function z=cos(x 9
+y 8
). ∂x
∂z
​
=9x 8
cos(x 9
+y 2
) ∂x
∂z
​
=−9x 10
sin(x 9
+y 9
) ∂x
∂z
​
=9x 10
cos(x 10
+y 10
) ∂x
∂z
​
=−9x 8
sin(x 9
+y 8
) ∂x
∂z
​
=9x 10
sin(x 10
+y 10
)