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anonymous
 one year ago
If f(x)= x^2/(4+x)/ find f "(4).
This is what I have done so far:
f(x)=x^2/(4+x) =
f '(x)=(4+x)(2x)x^2(4)/(4+x)^2=8x+2x^24x^2/(4+x)^2=x^2^2+8x/(4+x)^2=
f "(x)=(x^2+16x+16)(4x+8)(2x^2+8x)(4x+8)/(x^2+16x+16)^2
After that, this is the part that I am stuck on:
(4x+8)(x^2+16x+162x^28x)/[(x+4)^2]^2=(4x^2+8)(3x^2+8x+16)/[(x+4)^2]^2=
anonymous
 one year ago
If f(x)= x^2/(4+x)/ find f "(4). This is what I have done so far: f(x)=x^2/(4+x) = f '(x)=(4+x)(2x)x^2(4)/(4+x)^2=8x+2x^24x^2/(4+x)^2=x^2^2+8x/(4+x)^2= f "(x)=(x^2+16x+16)(4x+8)(2x^2+8x)(4x+8)/(x^2+16x+16)^2 After that, this is the part that I am stuck on: (4x+8)(x^2+16x+162x^28x)/[(x+4)^2]^2=(4x^2+8)(3x^2+8x+16)/[(x+4)^2]^2=

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freckles
 one year ago
Best ResponseYou've already chosen the best response.1derivative of (4+x) is 1.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0That is what my professor gave me...

freckles
 one year ago
Best ResponseYou've already chosen the best response.1still doesn't change that fact that d(4+x)/dx=d(4)/dx+d(x)/dx=0+1=1 and not 4...

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0He wants us to work this out by hand.

freckles
 one year ago
Best ResponseYou've already chosen the best response.1your professor probably made a little mistake then

freckles
 one year ago
Best ResponseYou've already chosen the best response.1\[f'(x)=\frac{(4+x)(2x)x^2 \color{red}{(1)}}{(4+x)^2}\]

freckles
 one year ago
Best ResponseYou've already chosen the best response.1@ElfQueen are you understanding?
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