Find the second derivative of?

Question

Find the second derivative of

f (x) = 4/x + 5

Let me reitterate.....I am looking for reassurance that I am doing this correctly, not looking for you to do my homework for me, just want to see if you get the same answers as me, thanks.

Answer 1

f'(x) = [4/(x+5)^2]*-1 = -4/(x+5)^2

f''(x) = [-4/(x+5)^3]*-2 = 8/(x+5)^3

EDIT: It wasn't meant to be derogatory Smarty. I have just seen one too many people on here who expect everyone to do their homework for them... sorry for jumping to conclusions...

Answer 2

f'(x) = unfavourable for all x the only element it somewhat is reducing for all values will be a function it somewhat is self sustaining of any value. this signifies that the first by-product is a continuing, ok, the position ok < 0. f''(x) = ? The by-product of a consistent is 0. accordingly the 2d by-product of f''(x) is 0. Graph: combine f'(x) = okay to examine f(x) INTEG(f'(x) = ok) = f(x) = kx, the position ok< 0 So the graph of this function is a diagonal line going from north and west of 0 to south and east of 0 and passing through the starting place (0,0). The slope relies upon upon ok

Answer 3

Just rewrite 4/x as 4*x^-1, then use the power rule as normal.
4/x + 5 = 4*x^-1 + 5

First derivative:
-4*x^-2
Second derivative:
8*x^-3

EDIT: This assumes your function is (4/x) + 5.
If it really is 4/(x+5), then the next response has it covered.

Answer 4

Use this:
type your result,integrate it twice,and if the answer is 4/x+5 then you`ve done a good job
http://integrals.wolfram.com/index.jsp

Answer 5

f(x)=4/x+5
f'(x)=4*-1/x^2=-4/x^2
f"(x)=-4*-2*x^-3
=8/x^3 ans

Answer 6

f'(x)=-4/x^2
f''(x)=8/x^3