5.The prices of input (x_1,x_2,x_3,x_4) are (4, 1, 3, 2)

a. If the production function is given by f(x_1,x_2 )=min{x_1,x_2}, what is the minimum cost of producing one unit of output?

b. If the production function is given by f(x_1,x_2 )=x_3+x_4, what is the minimum cost of producing one unit of output?