`a) 3x - 1/4 = 5`
`=> 3x = 5 + 1/4`
`=> 3x = 20/4 + 1/4`
`=> 3x = 21/4`
`=> x = 21/4 : 3`
`=> x = 21/4 . 1/3`
`=> x = 21/12`
`=> x = 7/4`
Vậy `x = 7/4`
__
`b) 22/3 : ( x + 2 ) = 15/6`
`=> x+2 = 22/3 : 15/6`
`=> x + 2 = 22/3 . 6/15`
`=> x + 2 = 132/45`
`=> x + 2 = 44/15`
`=> x = 44/15 - 2`
`=> x = 44/15 - 30/15`
`=> x = 14/15`
Vậy `x = 14/15`
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`c) ( 2x + 1 )^4 = 625/81`
`=>(2x + 1)^4 = (5/3)^4`
`=>2x + 1 = 5/3`
`=> 2x = 5/3 - 1`
`=> 2x = 5/3 - 3/3`
`=> 2x = 2/3`
`=> x = 2/3 : 2`
`=> x = 2/3 . 1/2`
`=> x = 1/3`
Vậy `x = 1/3`
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`d) 7/2 - 2x =` \(\sqrt{4}\)
`=> 7/2 - 2x = 2`
`=> 2x = 7/2 - 2`
`=> 2x = 7/2 - 4/2`
`=> 2x = 3/2`
`=> x = 3/2 : 2`
`=> x = 3/2 . 1/2`
`=> x = 3/4`
Vậy `x = 3/4`
__
`e)` `x/27 = -2/{3,6} `
`=> x/27 = -5/9`
`=>` `9x = -5 . 27 `
`=> 9x = -135`
`=> x = -135 : 9`
`=> x = -15 `
Vậy `x =- 15`
__
`f) 1/2 - 3/5x = -1/7`
`=> 3/5x = 1/2 -(-1/7)`
`=> 3/5x = 1/2 + 1/7`
`=> 3/5x = 7/14 + 2/14`
`=> 3/5x = 9/14`
`=> x = 9/14 : 3/5`
`=> x = 9/14 . 5/3`
`=> x = 45/42`
`=> x = 15/14`
Vậy `x = 15/14`
