find the derivitive f(x) = -4/x^2 use the limit process
Using fx=(x+Dx)-fx/Dx
I get -4/(x+Dx)^2/x^2 + 4/x^2 and get lost in the math - am I on the right track?
Hello,
$\displaystyle f'(x)=\frac{f(x+Dx)-f(x)}{Dx}$
$\displaystyle f({\color{red}x+Dx})=\frac{-4}{({\color{red}x+Dx})^2}$
---> $\displaystyle f'(x)=\frac{\frac{-4}{(x+Dx)^2}+\frac{4}{x^2}}{Dx}$
Did you catch your mistake ? Now, try to simplify (show your work, it'd be better)
It's time to get UNlost. You just have to sort through it.
1) Fix your notation:
These are NOT the same:
x+3/5 and (x+3)/5
Remember your Order of Operations.
2) Don't write things that make no sense.
You have: fx=(x+Dx)-fx/Dx
Notice how "fx" is on both sides. I'm sure you didn't mean that. Plus, there's and 'f' missing on the right -- f(x+Dx)?