1. Tính nhanh a) 15+23+(-25)+(-23) b)-17+50+17+(-50) c) 48+(-12)+(-48)+12 d) -23 . 63+23 . 21 – 58 e) -25 . 53+25 . 17+25 . 17 . 22 f) -27 . 48+27 . 6

0 bình luận về “1. Tính nhanh a) 15+23+(-25)+(-23) b)-17+50+17+(-50) c) 48+(-12)+(-48)+12 d) -23 . 63+23 . 21 – 58 e) -25 . 53+25 . 17+25 . 17 . 22 f) -27 . 48+27 . 6”

1. a) 15+23+(-25)+(-23)

   =(15-25)+(23-23)

   =-10+0

   =-10

   b)-17+50+17+(-50)

   =(-17+17)+(50-50)

   =0+0

   =0

   c) 48+(-12)+(-48)+12

   =(48-48)+(-12+12)

   =0+0

   =0

   d) -23 . 63+23 . 21 – 58

   =23.(-63+23)-58

   =-23.40-58

   =-920-58

   =-978

   e) -25 . 53+25 . 17+25 . 17 . 22

   =-25 . 53+25 . 17+25 . 374

   =25.(-53+17+374)

   =25.338

   =8450

   f) -27 . 48+27 . 62 – 27 . 10

   =27.(-48+62-10)

   =27.4

   =108.

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