Question

a)(19x + 2.5² ):14=(13-8)² - 4²

b)2.3^x=10.3¹²+8.27⁴

c)x² - [666:(24-13)]=7

Answer 1

a) `(19xx + 2.5^2) : 14 = (13-8)^2 - 4^2 `

`(19x + 2.25) : 14 = 5^2 - 4^2`

`(19xx + 50) : 14 = 25 - 16 `

`(19xx+50) : 14 = 9`

`19xx + 50 = 9.14`

`19xx+50 = 126`

`19x = 126 - 50`

`19x = 76` 

`x = 76 : 19` 

`x = 4 `

Vậy `x=4`

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b) 2. $3^{x}$ = 10. $3^{12}$ + 8 . $27^{4}$

2 . $3^{x}$  = 10 . $3^{12}$  + 8 . (3³)^4 

2 . $3^{x}$  = 10 . $3^{12}$  + 8 . $3^{12}$ 

2 . $3^{x}$ = $3^{12}$ . ( 10+8)

2 . $3^{x}$ = $3^{12}$ . 18      

2 . $3^{x}$ = $3^{12}$ . $3^{2}$ . 2 

⇒ $3^{x}$  = $3^{12}$ . $3^{2}$ 

$3^{x}$  = $3^{14}$ 

`⇒ x = 14`

`Vậy x=14`    

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`c)`

`2x - [ 666 : ( 24 - 13 ) ] = 7`

`2x - [ 666 : 11 ] = 7`

`2x - 666/11 = 7`

`2x = 7 + 666/11`

`2x = 743/11`

`x = 743/22`

Vậy `x = 743/22`