Please explain how to solve all parts

Suppose U(x, y) = x0.5 y0.5. (a) Find the Hicksian demands using the Lagrangian multiplier method. (The constraint is U(x, y) 2 U.) (b) Find the expenditure function. (c) Show that the expenditure function is concave in Px. ( show that the second-order partial derivative of the expenditure function with respect to Px is negative.) (d) Without solving the utility-maximization problem, find the indirect utility function. (e) Without solving the utility-maximization problem, find the Marshallian demands