1998年1999年2000年新植公顷数100014001800荒沙地公顷数2520024000224001.人们买房时,随着楼层的升高,上、下楼耗费的精力增多,因此不满意度升高.当住第n层楼时,上、下楼造成的不满意度为n.但高处空气清新,噪声较小,环境较为安静,因此随楼层升高环境不满意度降低.设住第n层楼 In 1998, 1999, the number of hectares newly planted in 2000 was 100014001800. The number of hectares in deserted land was 25,2002,4000,224,001. When people bought a house, as the floor heightened, the energy spent on the upper and lower floors increased. Therefore, the degree of dissatisfaction increased. At the time of the building, the dissatisfaction caused by the upstairs and downstairs is n. However, the high altitude air is fresh, the noise is small, and the environment is relatively quiet. Therefore, the dissatisfaction of the environment is reduced with the increase of floors. The building is located on the nth floor.