Question

Help :( I know the answer but not how to get there. find indicated derivative d/du ((u)/(u-1))-((u)/(u+1))

Answer 1

Do you know the quotient rule?

Answer 2

yes

Answer 3

Just take the derivative of each fraction using the quotient rule and combine them

Answer 4

i get \[\frac{( u-1)-u }{ u-1^{2} } - \frac{( u+1)-u }{ u+1^2 }\]

Answer 5

:(

Answer 6

Ok so let's just say that the top is x and the denominator is y... x/y
the quotient rule would be:
\[ \frac{ (x' * y)-(y' * x)}{ y ^{2}}\]

Answer 7

yeah i tried the quotient rule for both and got that, not combined yet, i think i did it wrong though

Answer 8

The derivative of the first fraction would be:
\[ \frac{ (1*(x-1)) - (1*x)}{ (x-1)^{2}}\]

Answer 9

It looks like you just forgot to square the entire denominator

Answer 10

okay, i got that. now the second one right?

Answer 11

The second on looks the same way. Just make sure you square the entire denominator not just part of it!

Answer 12

i just forgot to put the parenthesis on the typing part lol, but i dont know how my math textbook got -[((u)/((u-1)^2) - ((u)/(u+1)^2)]

Answer 13

as the answer

Answer 14

hmm... that's not right! The numerators for both would be 1! I double checked it too! http://www.wolframalpha.com/input/?i=d%2Fdu+%28%28u%29%2F%28u-1%29%29-%28%28u%29%2F%28u%2B1%29%29

Answer 15

see, i hate when textbooks have typos :/ they make me think i did something wrong lmao. thanks

Answer 16

no problem!