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

Toán Lớp 7: tìm x biết a, 1 1/5 + 4/5 : x = 0,75 B 3. ( 5x + 2/3 ) ^ 2 = 4/3

Toán Lớp 7: tìm x biết
a, 1 1/5 + 4/5 : x = 0,75
B 3. ( 5x + 2/3 ) ^ 2 = 4/3

Comments ( 1 )

  1. a)
    1 1/5 + 4/5 : x = 0,75
    ⇔ 6/5 + 4/5 : x = 0,75
    ⇔4/5 : x = -9/20
    ⇔ x=4/5 : (-9/20)
    ⇔x=-16/9
    b)
    3. ( 5x + 2/3 ) ^ 2 = 4/3
    ⇔(5x+2/3)^2=4/9
    ⇔5x+2/3= ±(2/3)
    TH1:5x+2/3=2/3⇔5x=0⇔x=0
    TH2:5x+2/3=-2/3⇔5x=-4/3⇔x=-4/15
    Vậy x∈{0; -4/15}

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