When entering values of x in the function, it is observed that for k = 7 the results of f (x) displace 10 units. For this see the attached table. Therefore, for this case, the correct answer is k = 7 and the way to solve it is to substitute values of x in the given functions and see the results of f (x).I attach results.
As time goes by, the resale value of a computer tends to drop because it tends not to function as properly as it did before, and the quality of new computers on the market drives the price of older computers down. So you can expect that as the amount of time increases, the resale value will decrease, resulting in a negative correlation