a, 1/4x+5/9=1/3 b, 3/4-(x-2/5)=11/12 c, /x+1/3/+1=4 d,27^x=3^x+2

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1. Đáp án + Giải thích các bước giải:

   Ta có :

   `a,\frac{1}{4}x+\frac{5}{9}=\frac{1}{3}`

   `→\frac{1}{4}x=-\frac{2}{9}`

   `→x=-\frac{8}{9}`

   `b,\frac{3}{4}-(x-\frac{2}{5})=\frac{11}{12}`

   `→x-\frac{2}{5}=-\frac{1}{6}`

   `→x=\frac{7}{30}`

   `c,|x+\frac{1}{3}|+1=4`

   `→|x+\frac{1}{3}|=3`

   `→` \(\left[ \begin{array}{l}x+\frac{1}{3}=3\\x+\frac{1}{3}=-3\end{array} \right.\) 

   `→` \(\left[ \begin{array}{l}x=\frac{8}{3}\\x=-\frac{10}{3}\end{array} \right.\) 

   Vậy `x∈{\frac{8}{3};-\frac{10}{3}}`

   `d,27^x=3^{x+2}`

   `→(3^3)^x=3^{x+2}`

   `→3^{3x}=3^{x+2}`

   `→3x=x+2`

   `→3x-x=2`

   `→2x=2`

   `→x=1`

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2. Đáp án:

    

   Giải thích các bước giải:

   `a) 1/4x+5/9=1/3`

   `=> 1/4x=1/3-5/9`

   `=> 1/4x=-2/9`

   `=> x=(-2/9):1/4`

   `=> x=-8/9`

   `b) 3/4-(x-2/5)=11/2`

   `=> x-2/5=3/4-11/2`

   `=> x-2/5=-1/6`

   `=> x=(-1/6)+2/5`

   `=> x=7/30`

   `c) |x+1/3|+1=4`

   `=> |x+1/3|=3`

   `=>` \(\left[ \begin{array}{l}x+\dfrac{1}{3}=3\\x+\dfrac{1}{3}=-3\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=\dfrac{8}{3}\\x=-\dfrac{10}{3}\end{array} \right.\) 

   `d) 27^x=3^(x+2)`

   `=> 3^(3x)=3^(x+2)`

   `=> 3x=x+2`

   `=> 3x-x=2`

   `=> 2x=2`

   `=> x=1`

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