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# differentiating from first principles watch

1. f(x) = 1/(1-x)^2

i know how to do it but i end up with some complex fraction over fraction which cant cancel which prob means im doing it wrong could i get some help with it please

just to check f(x+deltax) means 1/(1-(x+deltax))^2 right?
2. Yes.
3. (Original post by eugenius 8)
f(x) = 1/(1-x)^2

i know how to do it but i end up with some complex fraction over fraction which cant cancel which prob means im doing it wrong could i get some help with it please

just to check f(x+deltax) means 1/(1-(x+deltax))^2 right?
would it not be easier to differentiate (1-x)^-2
4. oh crap i meant 1/(1-x^2)
5. (Original post by Chaoslord)
would it not be easier to differentiate (1-x)^-2
Differentiate from first principles means you can't "just differentiate"
6. (Original post by SimonM)
Differentiate from first principles means you can't "just differentiate"

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