Đáp án:
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`a,`
`(2/3)^8 × x = (2/3)^{11}`
`↔ x = (2/3)^{11} ÷ (2/3)^8`
`↔ x = (2/3)^{11 - 8}`
`↔ x = (2/3)^3`
`↔ x = 8/27`
Vậy `x=8/27`
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`b,`
`x ÷(-1/2)^4 = (-1)/2`
`↔ x = (-1)/2 × (-1/2)^4`
`↔ x = (-1/2)^{1 + 4}`
`↔ x = (-1/2)^5`
`↔ x = (-1)/32`
Vậy `x=(-1)/32`
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`c,`
`(x-5)^3 = 8`
`↔ (x-5)^3 = 2^3`
`↔ x - 5 = 2`
`↔ x =2 + 5`
`↔ x = 7`
Vậy `x=7`
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`d,`
`(2x+1)^4 = 1/256`
`↔` \(\left[ \begin{array}{l}(2x+1)^4=(\dfrac{1}{4})^4\\(2x+1)^4=(\dfrac{-1}{4})^4\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}2x+1=\dfrac{1}{4}\\2x+1=\dfrac{-1}{4}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}2x=\dfrac{1}{4}-1\\2x=\dfrac{-1}{4}-1\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}2x=\dfrac{-3}{4}\\2x=\dfrac{-5}{4}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=\dfrac{-3}{4}÷2\\x=\dfrac{-5}{4}÷2\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=\dfrac{-3}{8}\\x=\dfrac{-5}{8}\end{array} \right.\)
Vậy `x=(-3)/8` hoặc `x=(-5)/8`
