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Solve. x^2−5x−8=0

 

Enter the answers as exact values

 

x=_______or  x=__________

 

Thanks much!

Guest Oct 22, 2018
 #1
avatar+90969 
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x^2  - 5x  - 8  = 0    add 8 to both sides

 

x^2  - 5x   = 8

 

Take  1/2 of 5  = 5/2....square it  = 25/4    .....add to both sides

 

x^2 - 5x  + 25/4  =  8 + 25/4       factor the left side, simpliify the right

 

(x - 5/2)^2  =  57/4      take both roots

 

x - 5/2  =  ± √ [ 57 / 4 ]

 

x - 5/2  = ± √57 / 2      add 5/2 to both sides

 

x  = 5/2  + √57/ 2          or   x  =  5/2   - √57 / 2

 

 

cool cool cool

CPhill  Oct 22, 2018
 #2
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Thank you!!

Guest Oct 23, 2018

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