Câu 2 : a) (123-27)+(27+13-123) b) (-1579)-(12-1579) c) (42-69+17)-(42+17) d) (-18+29)+(158+18-29)

10/09/2024

2 bình luận về “Câu 2 : a) (123-27)+(27+13-123) b) (-1579)-(12-1579) c) (42-69+17)-(42+17) d) (-18+29)+(158+18-29) <p”

1. Giải đáp:

   a) (123-27)+(27+13-123)                           b) (-1579)-(12-1579) 

   =123-27+27+13-123                                 = -1579-12+1579

   =(123-123)+(27-27)+13                             =(-1579+1579)-12

   =0+0+13                                                    =0-12

   =13                                                             =-12

   c) (42-69+17)-(42+17)                                d) (-18+29)+(158+18-29)

   =42-69+17-42-17                                      =-18+29+158+18-29

   =(42-42)+69+(17-17)                                 =(-18+18)+(29-29)+158

   =0+69+0                                                    =0+0+158

   =69                                                             =158

   e) 271-[(-43)+271-(-17)]                             f) -144-[29-(+144)-(+144)]

   =271+43-271+(-17)                                   =-144-29+144-144

   =(271-271)-[(43+(17)]                                =-144-29

   =0+26                                                         =(-144+144)-(29-144)

   =26                                                              =0-(-115)

                                                                        =115

    

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2. $#Hy$

   @ Phương pháp làm bài:

   Cộng trừ từ ngoặc tròn trước “(…)” rồi đến ngoặc vuông “[…]”.

   2 dấu + = 1 dấu –

   “Câu 2: 

   a) (123-27)+(27+13-123)
   = 123-27 + 27 + 13 – 123
   = (123 – 123) + (-27 + 27) + 13
   = 13

   b) (-1579)-(12-1579)
   = -1579 – 12 + 1579
   = (-1579 + 1579) – 12
   = -12

   c) (42-69+17)-(42+17)
   = 42-69+17 – 42 – 17
   = (42 – 42) – 69 + (17 – 17)
   = -69

   d) (-18+29)+(158+18-29)
   = -18+29 +158+18-29
   = (-18 + 18) + (29 – 29) + 158
   = 158
   e) 271-[(-43)+271-(-17)]
   = 271-[-43 +271 +17]
   = 271 + 43 – 271 – 17
   = (271 – 271) + 43 – 17
   = 26

   f) -144-[29-(+144)-(+144)]
   = -144 – [ 29 – 144 – 144]
   = -144 – 29 + 144 + 144
   = (-144 + 144) – 29 + 144
   = 115

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