What is the difference between deriving and deriving using first principles ?

for example how would you use first principles to find the derivative of y=7/(rootx + 6)

and y = 1 / 2x

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- Mar 26th 2009, 10:03 PMnoshDerivatives and first principles ??? help please
What is the difference between deriving and deriving using first principles ?

for example how would you use first principles to find the derivative of y=7/(rootx + 6)

and y = 1 / 2x - Mar 26th 2009, 10:25 PMJhevon
Finding derivatives by first principles means to use the definition of the derivative. recall that we define the derivative of a function $\displaystyle f(x)$ as follows

$\displaystyle f'(x) = \lim_{h \to 0} \frac {f(x + h) - f(x)}h$

provided the limit exists.

now use that to find the derivatives. you can check your answers by doing the derivatives the short way