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f(x)=sqrt(x+4)+sqrt(4-x)

 

Find X an Y intercepts

 Apr 30, 2016
 #1
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To find the y intercept, let x = 0  ....and we have.....

 

f(x)=sqrt(0+4)+sqrt(4-0)  =  sqrt(4) + sqrt(4)  =  2 + 2  = 4   =  (0,4)

 

To find the x intercepts, let y = 0

 

0 = sqrt (x + 4)  + sqrt(4 -x)     ....  ( 1)   subtract sqrt (4 - x)  from both sides

 

-sqrt(4 - x)  = sqrt (x + 4)    ....  (2)    square both sides

 

4 - x   = x + 4     add x to both sides......subtract 4 from both sides

 

0  = 2x     divide both sides by 2

 

0 = x     

 

However.....note that  x = 0   makes (1) untrue......it's an extraneous solution produced by squaring both sides of (2)......there aren't any x intercepts  - as shown by the following graph :

 

 

https://www.desmos.com/calculator/dm9rxpqizk

 

 

cool cool cool

 Apr 30, 2016

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