Question

If y=xlog(x/(a+bx), show that d2y/dx2 = 1/x * (a/ a + bx)^2

Please help I need the solution by today

Answer 1

ugh..this is gonna be long...

Answer 2

have you tried it yet?

Answer 3

Yes of course

Answer 4

and what did you get?

Answer 5

After differentiating twice, I got

Answer 6

(a+bx+ab/(a+bx)^2) + a/x(a+bx)

Answer 7

Umm man, it's kinda urgent.. Do u mind telling me how to go about it? Thanks!

Answer 8

Such a beast of a question. Check out these links

first derivative
http://www.wolframalpha.com/input/?i=xlog%28x%2F%28a%2Bbx%29

2nd derivative
http://www.wolframalpha.com/input/?i=%28a%2B%28a%2Bb+x%29+log%28x%2F%28a%2Bb+x%29%29%29%2F%28a%2Bb+x%29&lk=1&a=ClashPrefs_*Math-

in that second link it's got what you want. Theres probably a clever-er way of doing it tho

Answer 9

Whoa what was that
Can you explain? Or tell me the clever-er way?

Answer 10

I am not sure of the clever-er way or if it exists but on those pages, scroll down till you see the derivative part then click show working.

Answer 11

then see if you can understand whats it is doing. messy question tho

Answer 12

Right...

Answer 13

haha yeah...