Mình xin hay nhất ^^
Câu 1 :
`a. 4/5 - 3/4`
`= 16/20 - 15/20`
`=1/20`
`b, -8/9 : 16/27`
`=-8/9 . 27/16`
`=-128/243`
`c,-2,4 + 1,5 : ( 1 - 2/3)`
` =-2,4 +1,5 : 1/3`
=`-12/5 + 3/2 : 1/3`
`=-12/5 + 9/2`
`=-24/12 + 45/12`
`= 21/12`
`d, -3/4 + 5/6 . 3/2 - 6/5`
`= -3/4 + 5/4 - 6/5`
`= 1/2 - 6/5`
`= 5/10 - 12/10`
`= -7/10`
câu 2.
`a. 1/2 - x = 5/3`
`⇔ x = 1/2 - 5/3`
`⇔ x = -7/6`
Vậy `x = -7/6`
`b.11/12x + 3/4 = 1/6`
`⇔11/12.x = 1/6 - 3/4`
`⇔11/12.x= -7/12`
`⇔x = -7/12 : 11/12`
`⇒x = -7/11`
Vậy `x = -7/11`
`c.60%x + 2/3x = 684`
`⇔ 3/5.x + 2/3.x = 684`
`⇔x.(3/5 + 2/3) = 684`
`⇔x. 19/15 = 684`
`⇔x = 684 : 19/15`
`⇒x = 10260/19`
`⇒ x = 540`
Vậy`x = 540`
d.`l2x + 1l+ 2 = 5/2`
`⇔ l2x + 1l = 5/2 - 2`
`⇔l2x + 1l = 1/2`
`⇔ 2x + 1 = 1/2`
`2x + 1 = -1/2`
`⇔ 2x = -1/2`
`2x = 1/2`
`⇔x = -1/4`
`x = 1/4`
`Vậy x∈{±1/4}`
