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

Toán Lớp 7: $(1/3)^{2x-1}$ – $(1/3)^{2}$ =$\frac{-2}{27}$

Toán Lớp 7: $(1/3)^{2x-1}$ – $(1/3)^{2}$ =$\frac{-2}{27}$

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    (1/3)^(2x – 1) – (1/3)^2 = (-2)/27
    ⇒ (1/3)^(2x – 1) – 1/9 = (-2)/27
    ⇒ (1/3)^(2x – 1) = (-2)/27 + 1/9 = 1/27
    ⇒ (1/3)^(2x – 1) = (1/3)^3
    ⇒ 2x – 1 = 3
    ⇒ 2x = 4
    ⇒ x = 2
    Vậy  x = 2

  2. (1/3)^(2x – 1) – (1/3)^2 = -2/27
    (1/3)^(2x – 1) – 1/9 = -2/27
    (1/3)^(2x – 1) = -2/27 + 1/9
    (1/3)^(2x – 1) = 1/27
    (1/3)^(2x – 1) = (1/3)^3
    => 2x – 1 = 3
    2x = 3 + 1
    2x = 4
    x = 4 : 2
    x = 2
    Vậy x = 2

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