The table gives a country's gross domestic product (GDP) (in trillions of dollars) for selected years from 2005 and projected to 2070. Complete parts (a) through (c) below. GDP GDP Year Year Year ($ trillions) ($ trillions) GDP ($ trillions) 46.761 2055 2005 12.141 2030 2010 16.169 2035 2015 21.259 2040 2020 27.684 2045 2025 35.918 2050 173.173 61.100 2060 224.043 79.674 2065 290.041 103.445 2070 375.214 133.914 a. Find the best-fitting quadratic model for the data, with x equal to number of years after 2000. (Type integers or decimals rounded to three decimal places as needed.)