199x48+199=199x(48+1)=(200-1)x49=200x49-49=9800-49=9751
199×48+199=199×(48+1)=199×(50-1)=(200-1)×(50-1)=200×50-200-50+1=10000-250+1=9751
199×48+199=199×(48+1)=(200-1)×49=200×49-49=9751
楼上答案清晰哦