Final answer:
The correct equation for the cost of shipping a package weighing x pounds with the stated pricing structure is f(x) = 6 + 2(x - 1), where x > 0.
Step-by-step explanation:
The equation that represents the cost of shipping a package that weighs x pounds can be found by taking into account the initial cost and the cost for each additional pound. Given the shipping company charges $6 for up to 1 pound and $2 for each additional pound or portion thereof, the cost equation is f(x) = 6 + 2(x - 1), where x > 0 and we assume x to be the number of pounds rounded up to the nearest whole number if it's not already an integer. According to this, the first pound is covered by the initial $6, and the additional pounds are charged at $2 per pound.