$#Đáp án + Giải thích các bước giải:$
`1.`
`( - 5/2x + 1 ) ^ 2 - 10 = - 31/4`
`→( - 5/2x + 1 ) ^ 2= 9/4`
+ TH`1:`
`( - 5/2x + 1 ) ^ 2= 9/4`
`→( - 5/2x + 1 ) ^ 2= (3/2)^2`
`→ - 5/2x + 1 = 4/2`
`→ - 5/2 x = 1`
`→ x=-2/5`
+ TH`2:`
`( - 5/2x + 1 ) ^ 2= 9/4`
`→( - 5/2x + 1 ) ^ 2= (-3/2)^2`
`→ - 5/2x + 1 = -3/2`
`→ - 5/2 x = -5/2`
`→ x=1`
Vậy `x∈{-2/5;1}`
-------------------------------------------------
`2.`
`( - 1/2 x + 2/3 ) : -5/7 = 28 / 15`
`→- 1/2 x + 2/3 = -4/3`
`→- 1/2 x = -2`
`→x=4`
Vậy `x=4`
----------------------------------------------------
`1/3 | x - 2 | - 3/7 = 4/5`
`→1/3 | x - 2 | = 43/35`
`→ x - 1 = 129/35`
+ TH`1:`
`x - 1 = 129/35`
`→ x = 164/35`
+ TH`2:`
`x - 1 = -129/35`
`→x = -94/35`
Vậy `x∈{164/35 ; -94/35}`
$#Cam$
$#XIN HAY NHẤT CHO NHÓM AK$
