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

Toán Lớp 7: Tìm `x` `m)\frac{x-1}{x+5}=6/7` `k)\frac{(X+3)^5}{(x+3)^2}=64/27`

Toán Lớp 7: Tìm x
m)\frac{x-1}{x+5}=6/7
k)\frac{(X+3)^5}{(x+3)^2}=64/27

Comments ( 2 )

  1.  Giải đáp:
     m) x= 37    k) x= $\frac{-5}{3}$ hoặc x= $\frac{-13}{3}$ 
    Lời giải và giải thích chi tiết:
    m)   $\frac{x-1}{x+5}$ =$\frac{6}{7}$
    ⇒ 7(x-1) = 6(x+5)
         7x -7 = 6x +30
         7x- 6x= 30 + 7
        x= 37
    k)  $\frac{(x+3)^{5} }{(x+3)^{2} }$ =$\frac{64}{27}$
    ⇒$(x+3)^{3}$ = $\frac{64}{27}$
    $(x+3)^{3}$ = $(\frac{4}{3} )^{2}$
    ⇒\(\left[ \begin{array}{l}x+3=\frac{4}{3}\\x+3=\frac{-4}{3}\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}x=\frac{-5}{3}\\x+3=\frac{-13}{3}\end{array} \right.\) 

  2. m)
    {x-1}/{x+5} = 6/7
    <=> 7. ( x – 1 ) = 6. ( x + 5 )
    <=> 7x – 7 = 6x + 30
    <=> 7x – 6x = 30 + 7
    <=> x = 37
      $\text{ Vậy x = 37 }$
    k)
    {(x+3)^5}/{(x+3)^2} = 64/27   ( x $\ne$ -3 )
    <=> ( x + 3 )^3 = 64/27
    <=> ( x + 3 )^3 = (4/3)^3
    <=> x + 3 = 4/3
    <=> x = 4/3 – 3
    <=> -5/3
      $\text{ Vậy x = $\dfrac{-5}{3}$ }$
     

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