Đáp án + Giải thích các bước giải:
`a)` `2x + 8/3 = \sqrt{1/9}`
`2x + 8/3 = 1/3`
`2x = 1/3 - 8/3`
`2x = (-7)/3`
`x = (-7)/3 : 2`
`x = (-7)/3 . 1/2`
`x = (-7)/6`
Vậy `x = (-7)/6`
`b)` `|x - 3/4| - 1 = 1/2`
`|x - 3/4| = 1/2 + 1`
` |x - 3/4| = 1/2 + 2/2`
` |x - 3/4| = 3/2`
`=>`\(\left[ \begin{array}{l}x - \dfrac{3}{4} = \dfrac{3}{2}\\x - \dfrac{3}{4} = \dfrac{-3}{2}\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=\dfrac{3}{2} + \dfrac{3}{4}\\x=\dfrac{-3}{2} + \dfrac{3}{4}\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=\dfrac{9}{4}\\x=\dfrac{-3}{4}\end{array} \right.\)
Vậy `x in {9/4; (-3)/4}`
`c)` `2. 3^(x+1) + 7. 3^(x+2) = 207`
`3^(x+1) . (2 + 7.3) = 207`
`3^(x+1) . (2 + 21) = 207`
` 3^(x+1) . 23 = 207`
`3^(x+1) = 207 : 23`
`3^(x+1) = 9`
`3^(x+1) = 3^2`
`=>` `x + 1 = 2`
`x = 2 - 1`
`x = 1`
Vậy `x = 1`
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