` \color{#0074D9}{#n}\color{#0088DD}{q}\color{#3399FF}{o}\color{#66AAFF}{c}\color{#99CCFF}{c} `
`9) (x+0,7)^3 = -27 `

`(x+0,7)^3 = (-3)^3 `

`x+0,7 = -3 `

`x = - 3 - 0,7 `

`x = -3,7`

Vậy `x=-3,7`

`10) (2/3x- 1/3)^5 = 1/243 `

`(2/3x - 1/3)^5 = 1^5/3^5 `

`(2/3x - 1/3)^5 = (1/3)^5 `

`2/3x - 1/3 = 1/3 `

`2/3x = 1/3 + 1/3 `

`2/3x = 2/3 `

`x = 2/3 : 2/3 `

`x = 1 `

Vậy `x=1`

`11) (2/5 - 3x)^2 = 9/25 `

`(2/5 - 3x)^2 = 3^2/5^2 `

`(2/5 - 3x)^2 = (3/5)^2 `

`2/5 - 3x = +- 3/5 `

`2/5 - 3x = 3/5 ` hoặc `2/5 - 3x = -3/5 `

`TH1 : 2/5 - 3x = 3/5 `

`3x = 2/5 - 3/5 `

`3x = -1/5 `

`x = -1/5 : 3 `

`x = -1/5 . 1/3 `

`x = -1/15`

`TH2 : 2/5 - 3x = -3/5 `

`3x = 2/5 - (-3/5) `

`3x = 2/5 + 3/5 `

`3x = 5/5 `

`3x = 1 `

`x = 1 : 3 `

`x = 1/3 `

Vậy `x ∈ {-1/15 ; 1/3} `

`12) (2x-1)^10 = 49^5 `

`(2x-1)^10 = (7^2)^5 `

`(2x-1)^10 = 7^10 `

`2x - 1 = +- 7 `

`2x - 1 = 7 ` hoặc `2x - 1 = - 7 `

`TH1 : 2x - 1 = 7 `

`2x = 8 `

`x = 8 : 2 `

`x = 4`

`TH2 : 2x - 1 = -7 `

`2x = -6 `

`x = -6 : 2 `

`x = -3 `

Vậy `x ∈ {4;-3} `

`13) x : 5^2 = (3/5)^2 : 3^2 `

`x : 25 = 9/25 : 9 `

`x : 25 = 9/25 . 1/9 `

`x : 25 = 1/25 `

`x = 1/25 . 25 `

`x = 1 `

Vậy `x=1`

`14) (x-3/5)^2 = 4 `

`(x-3/5)^2 = 2^2 `

`x - 3/5 = +- 2 `

`x - 3/5 = 2 ` hoặc `x-3/5 = -2 `

`TH1 : x - 3/5 = 2 `

`x = 13/5 `

`TH2 : x - 3/5 = -2 `

`x = -7/5 `

Vậy `x ∈ {13/5 ; -7/5} `

`15) (x-1/4)^2 = 4/9 `

`(x-1/4)^2 = 2^2/3^2 `

`(x-1/4)^2 = (2/3)^2 `

`x - 1/4 = +- 2/3 `

`x - 1/4 = 2/3 ` hoặc `x-1/4 = -2/3 `

`TH1 : x - 1/4 = 2/3 `

`x = 11/12 `

`TH2 : x - 1/4 = -2/3 `

`x = -5/12 `

Vậy `x ∈ {11/12 ; -5/12} `

`16) (2x-5)^4 = -81 `

`(2x - 5)^4 >= 0 ` với mọi `x`

mà `-81 < 0 ` 

`=> ` Vô lý

Vậy phương trình vô nghiệm