Four major U.S. wireless carriers will sell an iPad-like tablet computer from Samsung Electronics, the companies said Thursday.Samsung and the service providers — AT&T, Sprint Nextel, T-Mobile USA and Verizon Wireless— didn’t say how much the Galaxy Tab will cost, or exactly when it will be on sale.Verizon Wireless said in a statement that it will start selling it “in the coming weeks,” and Sprint said it will do so “this fall.” T-Mobile and AT&T said they plan to sell it this holiday season.The Galaxy Tab has a 7-inch (17.7-centimeter) screen, half the size of the iPad. It runs Google Inc.’s Android smart phone software and can play Flash video from the Web, which the iPad can’t. It also has two cameras for videoconferencing, which the iPad lacks.The iPad starts at $499. The Tab will probably cost less, both because it’s smaller and because carriers will probably subsidize it when buyers sign up for two-year data service contracts.