f(x)=x³+3x+6

i need to find f^-1'(2)

do i need to find the inverse of f(x) before i derive it. or do i derive it first, then find the inverse, and then plug 2 in for x?

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- November 29th 2009, 02:36 PMjohnnyc418finding inverse
f(x)=x³+3x+6

i need to find f^-1'(2)

do i need to find the inverse of f(x) before i derive it. or do i derive it first, then find the inverse, and then plug 2 in for x? - November 29th 2009, 02:50 PMtonio

I suppose you already know that , when the derivative in the denominator is expressed in the same variable as the one of , of course.

So in this case , when x is expressed as function of y, and we don't have the faintest idea what is this...but we don't need to have: just check that as , then

Tonio - November 29th 2009, 02:51 PMskeeter
- November 29th 2009, 03:04 PMjohnnyc418
- November 29th 2009, 03:12 PMskeeter

since

so ...

unconfused now? - November 29th 2009, 03:14 PMjohnnyc418
yes thank you