Bài `1:`
`a)` `3/4` `+` `1/4` `:` `x` `=` `2`
`1/4` `:` `x` `=` `2-3/4`
`1/4:x= 5/4`
`x= 1/4:5/4`
`x = 1/4x4/5`
`x = 1/5`
Vậy `x=1/5`
`b) l3x-5l - l-3/2l=5`
`l3x-5l- 3/2 =5`
`l3x-5l = 5+3/2`
`l3x-5l = 13/2`
`=> 3x-5 = 13/2` hoặc `3x-5=-13/2`
`TH1: 3x-5=13/2` `TH2: 3x-5 = -13/2`
`3x = 13/2+5` `3x =-13/2 +5`
`3x = 23/2` `3x = -3/2`
`x = 23/2 :3` `x = -3/2 :3`
`x = 23/6` `x = -1/2`
Vậy `x=23/6` hoặc `x= -1/2`
`c) lx-1l +lxl =7`
Ta có: `7=3+4`
`lx-1l +lxl =3+4`
`⇒ x-1= 3`
`x = 3+1`
`x =4(TM)`
`⇒ x={-4,4}`
Bài `2`
`a) x.y + x-24 =4`
`x.y +x = 4+24`
`x.y+x = 28`
`x. y + x.1 =28`
`x.(y+1) = 28`
Ta có: `28= 7.(3+1)`
`= 4.(6+1)`
`= 28.(0+1)`
`= 1.(27+1)`
`⇒ x={7;4;28;1}`
`y={3;6;0;27}`
`b)`
`1/x - y/5 = 1/3`
`5/(x.5)-(y.3)/15=5/15`
`⇒ x.5=15`
`⇒ x =15:5`
`⇒ x =3`
`⇒ 5-y=5`
`⇒ y=5-5`
`⇒ y=0`
Vậy `x=3 y=0`
$#UMR$#
