giúp với sẽ cho 5 sao

` # Traam `

` 4^(2x + 1 ) + 4^(2x)= 80 `

` 4 . 4^(2x) + 4^(2x) = 80 `

` ( 4 + 1 ) . 4^(2x) = 80 `

` 5 . 4^(2x ) =80 `

` 4^(2x) = 80 : 5 `

` 4^(2x) = 16 `

` 4^(2x) = 4^2 `

` 2x= 2 `

` x = 2 : 2 `

` x = 1 `

Vậy ` x = 1 `

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` b ) `

` (2x - 17 ) . 5^6 = 5^9 `

` ( 2x - 17 ) = 5^9 : 5^6 `

` 2x - 17 = 5^3 `

` 2x - 17 = 125 `

` 2x = 125 + 17 `

` 2x = 142 `

` x = 142 : 2 `

` x = 71 `

Vậy ` x = 71 `

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` c ) `

` 20 + 5x = 5^5 : 5^3 `

` 20 + 5x = 5^2 `

` 20 + 5x = 25 `

` 5x = 25 - 20 `

` 5x = 5 `

` x = 5 : 5`

` x = 1 `

Vậy ` x = 1 `