OG详解-OG9 数学2 Q4

Choice B is correct. Adding the second equation in the given system to the first equation in the given system yields 3x+(-3x+y) =12+(-6), which is equivalent to y = 6.
Choice A is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors. Choice D is incorrect and may result from conceptual or calculation errors.