SOLUTION: Find f'(x) for f(x)=√(1-8x) using the definition of the derivative

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Question 975410: Find f'(x) for f(x)=√(1-8x) using the definition of the derivative
Found 2 solutions by stanbon, Edwin McCravy:
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
Find f'(x) for f(x)=√(1-8x) using the definition of the derivative
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f'(x) = (1/2)(1-8x)^(-1/2)*(-8)
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= -4/sqrt(1-8x)
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Cheers,
Stan H.
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Answer by Edwin McCravy(20055)   (Show Source): You can put this solution on YOUR website!
The other tutor did not use the definition, he just used the formula.



 

Multiply by 

 

Multiply out numerator (FOIL):

 





Cancel the h's:







Now we can substitute 0 for h 





The bottom terms are like terms:



Cancel the 2 into the 8:



Edwin
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