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Calculate: 8^x-2^(x+1)-4=0

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alexa0048 | Student, Grade 11 | (Level 3) eNoter

Posted February 5, 2013 at 4:10 PM via web

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Calculate: 8^x-2^(x+1)-4=0

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted February 5, 2013 at 6:08 PM (Answer #1)

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The equation `8^x-2^(x+1)-4=0` has to be solved.

`8^x-2^(x+1)-4=0`

=> `2^(3*x) - 2*2^x - 4 = 0`

Let `2^x = y`

=> `y^3 - 2y - 4 = 0`

The real solution of the equation is y = 2

`2^x = 2`

=> x = 1

The solution of the equation 8^x-2^(x+1)-4=0 is x = 1

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