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hoangvu9a8
2 năm trước
cho hệ phương trình x+y=1 (1) . Phương trình nào sau đây có thể kết hợp với (1) để được 1 hệ phương trình bậc nhất hai ẩn có vô số nghiệm A. 3x-2y =5 B. 3x+y =1 C. x++3y =9 D. 2x+2y =2
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