How do I find the derivative of f(x) = sqrt(x) without using the power rule?

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SUMMARY

The derivative of the function f(x) = sqrt(x) can be found using the limit definition of a derivative, specifically limh->0 (f(x+h) - f(x))/h. To solve this without employing the power rule, one must expand the term sqrt(x+h) and utilize the difference quotient. A common technique involves multiplying the numerator and denominator by the conjugate, sqrt(x+h) + sqrt(x), to simplify the expression. This method effectively eliminates the square root in the numerator, allowing for the limit to be evaluated.

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Homework Statement



Find the derivative of the function f(x) = sqrt(x).

(Bear in mind that cannot use the power rule or anything like it. I must use limh->0.)

Homework Equations



limh->0 (f(x+h) - f(x))/h

The Attempt at a Solution



I'm getting hung up on expanding out the sqrt(x+h) term. I'm having trouble with exponents less than 1.
 
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Write out the difference quotient and multiply numerator and denominator by sqrt(x-h)+sqrt(x). That's the usual trick.
 
Yea, you're definitely right. Thanks! Been a while since I had to do that.
 

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