Đáp án:
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`a,`
`(x + 5)/(-16) = 1/4`
`↔ (x + 5)×4=-16`
`↔ x + 5 = -16÷4`
`↔ x + 5 = -4`
`↔ x = -4 - 5`
`↔ x = -9`
Vậy `x=-9`
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`b,`
`(x-3/4) (x + 2/5) = 0`
`↔` \(\left[ \begin{array}{l}x-\dfrac{3}{4}=0\\x+\dfrac{2}{5}=0\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=0+\dfrac{3}{4}\\x=0-\dfrac{2}{5}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=\dfrac{3}{4}\\x=\dfrac{-2}{5}\end{array} \right.\)
Vậy `x=3/4` hoặc `x=(-2)/5`
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`c,`
`(x - 2/3) ÷ 1/3 + 5/6 = 9 5/6`
`↔ (x - 2/3) ÷ 1/3 = 9 5 /6 - 5/6`
`↔ (x-2/3)÷1/3 = 9`
`↔ x - 2/3 = 9 × 1/3`
`↔ x - 2/3 = 3`
`↔ x = 3 + 2/3`
`↔ x = 11/3`
Vậy `x=11/3`
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`d,`
`(x-3/7)^2 = 4`
`↔` \(\left[ \begin{array}{l}(x-\dfrac{3}{7})^2=2^2\\(x-\dfrac{3}{7})^2=(-2)^2\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x-\dfrac{3}{7}=2\\x-\dfrac{3}{7}=-2\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=2+\dfrac{3}{7}\\x=-2+\dfrac{3}{7}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=\dfrac{17}{7}\\x=\dfrac{-11}{7}\end{array} \right.\)
Vậy `x=17/7` hoặc `x=(-11)/7`
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`e,`
`-2 |1/2x - 1/3| + 3/2 = 1/4`
`↔ -2 |1/2x - 1/3| = 1/4 - 3/2`
`↔ -2 |1/2x - 1/3| = (-5)/4`
`↔ |1/2x - 1/3| = (-5)/4 ÷ (-2)`
`↔ |1/2x - 1/3| = 5/8`
`↔` \(\left[ \begin{array}{l}\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{5}{8}\\ \dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{-5}{8}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}\dfrac{1}{2}x=\dfrac{23}{24}\\ \dfrac{1}{2}x=\dfrac{-7}{24}\end{array} \right.\)
`↔` \(\left[ \begin{array}{l}x=\dfrac{23}{12}\\x=\dfrac{-7}{12}\end{array} \right.\)
Vậy `x=23/12` hoặc `x=(-7)/12`
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`f,`
`1/2x + 4/5 = 14/24x - 3/2`
`↔ 1/2x - 14/24x = -4/5 - 3/2`
`↔ (1/2 - 14/24)x = (-23)/10`
`↔ (-1)/12x = (-23)/10`
`↔ x = (-23)/10 ÷ (-1)/12`
`↔ x = 138/5`
Vậy `x=138/5`
