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the square root of (x+15) + (square root of x) =15, what is the value of "x".

Guest Aug 1, 2017
 #1
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sqrt ( x + 15)  +  sqrt (x)  = 15              subtract sqrt (x) from both sides

 

sqrt ( x + 15)   = 15  - sqrt (x)               square both sides

 

x + 15  =     225  - 30 sqrt (x)  + x        subtract x from both sides

 

15  = 225  - 30sqrt(x)                           rearrange as

 

30sqrt (x)  =  210                               divide both sides by 30

 

sqrt (x)  = 7                                         square both sides again

 

x  = 49

 

Check  

 

sqrt ( 49 + 15 )  + sqrt (49)  = 15   ???

 

sqrt (64)  + sqrt (49)   = 15   ??

 

8 + 7  = 15      OK!!!

 

 

 

cool cool cool

CPhill  Aug 1, 2017

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