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Using the limit definition of the derivative, find f'(2) if f(x)= sqrt (x+2)

 Feb 14, 2016
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[sqrt ( x + h + 2)  - sqrt( x + 2)]  / h  =         multiply top/bottom by [ sqrt(x + h + 2) - sqrt ( x + 2)]

 

[sqrt ( x + h + 2) - sqrt (x + 2)] [ sqrt( x + h + 2) + sqrt(x + 2)] / ( h * [sqrt(x + h + 2) + sqrt (x + 2) ] )

 

[ (x + h + 2)  - ( x + 2)] /  ( h * [sqrt ( x + h + 2)  + sqrt(x + 2)] )

 

h /  ( h * [sqrt ( x + h + 2)  + sqrt(x + 2)] )

 

1 / [ sqrt ( x + h + 2) + sqrt (x + 2) ]        let h →  0

 

1 [ sqrt ( x + 2)  + sqrt(x + 2) ] =

 

1 / [ 2 sqrt (x + 2)]

                                                              

And f ' (2)  =

 

1/ [2 sqrt (2 + 2)]  =

 

1 [ 2 sqrt (4) ] =

 

1/ [2 * 2] =

 

1/4

 

 

 

cool cool cool

 Feb 14, 2016

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