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

Toán Lớp 6: {2x – 1} mũ 2=5 mũ 4 x mũ 20 + 5 mũ 4=625

Toán Lớp 6: {2x – 1} mũ 2=5 mũ 4
x mũ 20 + 5 mũ 4=625

Comments ( 2 )

  1. ( 2x – 1)^2 = 5^4
    (2x – 1)^2 = 625
    (2x – 1)^2 =(+-25)^2
    ⇒ +) 2x – 1 = 25
             2x    = 25 + 1
            2x      = 26
              x      = 26 : 2
               x        = 13
    +) 2x – 1 = -25
     2x = -25 + 1
     2x = -24
      x =-24 : 2
    x = -12
    Vậy x∈ { 13; -12}
    x^20 + 5^4 = 625
    x^20 + 5^4 = 5^4
    x^20 = 5^4 – 5^4
    x^20 = 0
    x^20 = 0^20
    ⇒ x = 0
     Vậy x = 0

  2. 1.
    (2x  – 1)^2 = 5^4
    => (2x – 1)^2 = (5^2)^2
    => (2x – 1)^2 = 25^2
    => \(\left[ \begin{array}{l}(2x – 1)^2 – 25^2\\x=(2x – 1)^2 = (-25)^2\end{array} \right.\) 
    => \(\left[ \begin{array}{l}2x – 1 = 25\\2x – 1 = -25\end{array} \right.\) 
    => \(\left[ \begin{array}{l}2x =26\\2x  = -24\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=13\\x=-12\end{array} \right.\) 
    Vậy x ∈ {13 ; -12}
    2.
    x^20 + 5^4 = 625
    => x^20 + 625 = 625
    => x^20 = 625 – 625
    => x^20 = 0
    => x^20 = 0
    Vậy x = 0

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