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

Toán Lớp 7: | x +5/4 | =0 |2,3 – x – 2.1,2 | = 0,1

Toán Lớp 7: | x +5/4 | =0
|2,3 – x – 2.1,2 | = 0,1

Comments ( 2 )

  1. | x +5/4 | =0
    ⇔ x + 5/4 = 0
    ⇔ x = – 5/4
    —-
    |2,3 – x – 2.1,2 | = 0,1
    ⇔ |2,3 – x – 2,4 | = 0,1
    ⇔ |-0,1-x | = 0,1
    ⇔ |0,1+x | = 0,1
    ⇔ 0,1+x = ± 0,1
    ⇔ 0,1+x=0,1 hoặc 0,1+x=-0,1
    ⇔ x = 0 hoặc x = – 0,2

  2. a ) | x + $\frac{5}{4}$ | = 0
    ⇒ x + $\frac{5}{4}$ = 0
    x = 0 – $\frac{5}{4}$ = – $\frac{5}{4}$ 
     b ) | 2 , 3 – x – 2 . 12 | = 0 , 1
    | 2 , 3 – x – 2 , 4 | = 0 , 1
    TH1 : 2 , 3 – x – 2 , 4 = 0 , 1 
    2 , 3 – x = 0 , 1 + 2 , 4 = 2 , 5
    x = 2 , 3 – 2 , 5 = – 0 , 2
    TH2 : 2 , 3 – x – 2 , 4 = – 0 , 1
    2 , 3 – x = – 0 , 1 + 2 , 4 = 2 , 3
    x = 2 , 3 – 2 , 3 = 0
    ⇔ x = { – 0 , 2 ; 0 } 

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

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