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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: Tim x , biet a. x- 3/4 =5/-7 b. 100 – |x +1| = 90

Toán Lớp 7: Tim x , biet
a. x- 3/4 =5/-7 b. 100 – |x +1| = 90

Comments ( 2 )

  1. x-3/4=5/-7
    ⇔x-3/4=-5/7
    ⇔x=-5/7+3/4
    ⇔x=1/28
    Vậy x=1/28
    b,
    100-|x+1|=90
    ⇔|x+1|=100-90
    ⇔|x+1|=10
    ⇔x=±9
    Vậy x=±9
    $_Ativity_$
     

  2. a) x-3/4=5/-7
              x = -5/7 + 3/4
              x = -20/28 + 21/28
              x = 1/28
    Vậy x = 1/28
    b) 100 – | x+1 | = 90
    => | x+1| = 100 – 90
    => | x+1| = 10
    Trường hợp 1 :
    x + 1 = 10
            x= 10 – 1
            x= 9
    Trường hợp 2 : 
    x + 1 = -10 
            x= -10 – 1
            x= -11
    Vậy x = 9 hoặc x = -11

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222-9+11+12:2*14+14 = ? ( )