câu 1: a) -50+20 b)-30-10 c)-55+(-20) d) -99 +100-1+99 câu 2: Bỏ ngoặc

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câu 1: a) -50+20 b)-30-10 c)-55+(-20) d) -99 +100-1+99 câu 2: Bỏ ngoặc rùi tính a)-50-[-30-(20-30)-50] b) 25 +(30-25)-30 câu 3: tìm x a) 25+x =30-(-15) b) x+20 =-50 +25

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Ariana 3 tuần 2021-11-17T00:16:15+00:00 2 Answers 3 views 0

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    0
    2021-11-17T00:17:35+00:00

    câu 1

    a) -50+20=-30

    b)-30-10=-40

    c)-55+(-20)=-75

    d)-99+100-1+99=(-99+99)+(100-1)=0+99=99

    câu 2

    a)-50-[-30-(20-30)-50]

    =50-(-30)-20+30-50

    =80-20+30-50

    =60+30-50

    =90-50

    =40

    b)25+(30-25)-30

    =25+30-25-30

    =(25-25)+(30-30)

    =0+0=0

    câu 3

    a)25+x=30-(-15)

    25+x=45

    x=45-25

    x=20

    b)x+20=-50+25

    x+20=-25

    x=-25-20

    x=-45

    0
    2021-11-17T00:18:04+00:00

    câu 1 :

    a) -50+20 

    = – ( 50 – 20 )

    = – 30

     

    b) – 30 – 10

    = ( – 30 ) + ( -10 )

    = -40

    c) – 55 + ( – 20 )

    = – 75

    d) -99 +100-1+99       

    = ( – 99 + 99 ) + ( 100 – 1 )

    =   0 + 99

    = 99

    câu 2 :

    a)- 50 – [ – 30 – ( 20 – 30 ) – 50 ]

    = – 50 + 30 + ( 20 – 30 ) + 50

    = -50 + 30 +  20 – 30  + 50

    = ( -50 + 50 ) + ( 30 – 30 ) + 20

    = 20

    b) 25 + ( 30 – 25 ) – 30  

    = 25 + 30 – 25 – 30

    = ( 25 – 25 ) + ( 30 – 30 )

    = 0

    câu 3 :

    a) 25 + x = 30  – ( – 15 )

        25 + x = 30 + 15

        25 + x = 45

                x = 45 – 25

                x = 20

     

    b) x + 20 = -50 + 25

        x + 20 = – 25

        x          = -25 – 20

        x          = – 45

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