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Solve 0=4(e^(2x)) - e^(-x)

 Apr 4, 2015

Best Answer 

 #1
avatar+130553 
+5

 0=4(e^(2x)) - e^(-x)    rearrange

e^(-x)  = 4e^2x   (1)

1 /e^(x)  = 4e^(2x)  multilpy both sides by e^x   and divide both sides by  4

1/4 = e^(3x)   take the Ln of both sides

Ln(1/4) = Ln e^(3x)   and, by a log property, we can write

Ln(1/4)  = 3x Lne    and Lne = 1  ....so we have

Ln(1/4)  = 3x     divide both sides by 3

Ln(1/4)/3  = x =  about -0.462

 

Here's the graph of both sides of (1) above showing the approximate solution.......

https://www.desmos.com/calculator/u8u7qz89kc

 

  

 Apr 4, 2015
 #1
avatar+130553 
+5
Best Answer

 0=4(e^(2x)) - e^(-x)    rearrange

e^(-x)  = 4e^2x   (1)

1 /e^(x)  = 4e^(2x)  multilpy both sides by e^x   and divide both sides by  4

1/4 = e^(3x)   take the Ln of both sides

Ln(1/4) = Ln e^(3x)   and, by a log property, we can write

Ln(1/4)  = 3x Lne    and Lne = 1  ....so we have

Ln(1/4)  = 3x     divide both sides by 3

Ln(1/4)/3  = x =  about -0.462

 

Here's the graph of both sides of (1) above showing the approximate solution.......

https://www.desmos.com/calculator/u8u7qz89kc

 

  

CPhill Apr 4, 2015

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