The U.S. stock market is opening higher after DuPont Co. said it is exploring a sale of its performance chemicals unit and China pledged to maintain growth, AP reported. The Dow Jones industrial average was up 51 points to 15,595, helped by a 4 percent gain in DuPont\'s stock in early trading Tuesday. The Standard & Poor\'s 500 index climbed more than two points to 1,697. The Nasdaq is up five points to 3,605. Before the market opened, Chinese Premier Li Keqiang vowed that the government would not let economic growth slip below 7 percent. That pushed up Asian and European markets. DuPont rose $2.30 to $59.49 after its announcement of a possible sale. There were mixed quarterly results from corporations. UPS posted a 4 percent profit decline. Wendy\'s beat Wall Street expectations.