Đáp án:
`4, 5/2 - 3(1/3 - x) = 1/4 - 7x`
`⇔ 5/2 - 1 + 3x = 1/4 - 7x`
`⇔ 3/2 + 3x + 7x = 1/4`
`⇔ 3/2 + 10x = 1/4`
`⇔ 10x =1/4 - 3/2 = 1/4 - 6/4`
`⇔ 10x = - 5/4`
`⇔ x = -5/4 : 10 = -5/4 . 1/10`
`⇒ x = - 1/8`
Vậy `x =- 1/8`
`5, 4(1/3 - x) + 1/2 = 5/6 + x`
`⇔ 4/3 - 4x + 1/2 = 5/6 + x`
`⇔ 11/6 - 4x - x = 5/6`
`⇔ 11/6 - 5x = 5/6`
`⇔ 5x = 11/6 - 5/6`
`⇔ 5x = 6/6 = 1`
`⇒ x = 1/5`
Vậy `x = 1/5`
`6, 3( 1/2 - x) - 5(x - 1/10) = -7/4`
`⇔ 3/2 - 3x - 5x + 5/10 = - 7/4`
`⇔ 3/2 + 1/2 - 8x = - 7/4`
`⇔ 2 - 8x = -7/4`
`⇔ 8x = 2 - (-7/4) = 8/4 - (-7/4)`
`⇔ 8x = 15/4`
`⇔ x = 15/4 : 8 = 15/4 . 1/8`
`⇔ x = 15/32`
Vậy `x = 15/32`
`7, 1/2 (4/5 - 3/2) + x = 5(x - 1/3)`
`⇔ 1/2 . (-7/10) + x = 5x - 5/3`
`⇔ -7/20 + x = 5x - 5/3`
`⇔ x - 5x = - 5/3 + 7/20`
`⇔ - 4x = - 79/60`
`⇔ x = -79/60 : (-4)`
`⇒ x = 79/240`
Vậy `x = 79/240`
`8, 4(3/4 + x) - 1/5 = 7x - 1/7`
`⇔ 3 + 4x - 1/5 = 7x - 1/7`
`⇔ 14/5 + 4x - 7x = - 1/7`
`⇔ 14/5 - 3x = -1/7`
`⇔ 3x = 14/5 - (-1/7)`
`⇔ 3x = 103/35`
`⇔ x = 103/35 : 3 = 103/35 . 1/3`
`⇒ x = 103/105`
Vậy `x = 103/105`
