y = f(x1, x2, x3, x4), x1 = g(x2, x3), x2 = h(x3)
(i) Find the partial derivative of y with respect to x3 in two ways, as in the example above.
(ii) Find the partial derivative of y with respect to x4 in two ways, as in the example above.
y = f(x1, x2, x3, x4), x1 = g(x2, x3), x2 = h(x3)
(i) Find the total derivative of y with respect to x3 in two ways, as in the example above.
(ii) Find the total derivative of y with respect to x4 in two ways, as in the example above.