A chemical company invested 1 million yuan at the end of 2007 to buy a set of sewage treatment equipment, the equipment's annual running costs are 0.5 million yuan, in addition to a certain amount of maintenance costs every year. Every first year maintenance fee of 20,000 yuan, due to equipment aging, the subsequent annual maintenance fee is 20,000 yuan more than the previous year.
Q: (1) Find the average annual cost of sewage treatment for the business using the equipment for X years, which is Y million dollars.? (2) Q To minimize the business's average annual sewage treatment costs, how many years will the business need to replace the equipment with new sewage treatment equipment?Solutions are shown in the diagram