H.1.2 and H.1.3 explanation please

Exercise H.1.2. Find all first and second order partial derivatives (including the cross derivatives) of the function f ( x, y ) = - 2 2 + y ? ) -1/2 Exercise H.1.3. A firm can produce quantity x of a product at cost x3 10x2 + 180x + 5. The firm faces the demand function where p is the price of the product. Find the profit-maximising level of output