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

Toán Lớp 7: Tìm x , biết : a) x – 1/2 = -2/3 ; b) 2/7 – x = 3/4 . giúp … ^^

Toán Lớp 7: Tìm x , biết :
a) x – 1/2 = -2/3 ; b) 2/7 – x = 3/4 .
giúp … ^^

Comments ( 2 )

  1. a) x – $\frac{1}{2}$ = -$\frac{2}{3}$ 
        x       = -$\frac{2}{3}$ + $\frac{1}{2}$
        x       = – $\frac{1}{6}$ 
    Vậy x = – $\frac{1}{6}$ 
    b) $\frac{2}{7}$ – x = $\frac{3}{4}$ 
                x =  $\frac{2}{7}$ – $\frac{3}{4}$
                x = – $\frac{13}{28}$ 
    Vậy x = – $\frac{13}{28}$ 

  2. Giải đáp + lời giải chi tiết :
    Xuu ~
    a/ x – $\dfrac{1}{2}$ = $\dfrac{-2}{3}$ .
        x                          = $\dfrac{-2}3{}$ – $\dfrac{1}{2}$ .
        x                            = $\dfrac{-4}{6}$ – $\dfrac{3}{6}$ .
        x                            = $\dfrac{-1}{6}$ .
    b/  $\dfrac{2}{7}$ – x = $\dfrac{3}{4}$ .
                                – x = $\dfrac{-3}{4}$ – $\dfrac{2}{7}$ .
                                – x = $\dfrac{-21}{28 }$ – $\dfrac{8}{28}$ .
                                – x = $\dfrac{-29}{28}$ .
                                – x = $\dfrac{29}{28}$ .
    Có thể làm theo cách khác : x = $\dfrac{2}{7}$ – $\dfrac{-3}{4}$ .
                                                x = $\dfrac{8}{28}$ – $\dfrac{-21}{28}$ .
     

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