• Support PF! Buy your school textbooks, materials and every day products Here!

Limits question ((x+1)/(x-1)-3)/(x-2)

  • Thread starter venger
  • Start date
  • #1
58
0

Homework Statement


F(x) = [x+1 / x-1] coordinates (2,3)


Homework Equations


First principle Mtang=(F(x)-F(a))/x-a
second principle
finding the derivatives at first glance

The Attempt at a Solution


Mtang=(F(x)-F(a))/x-a
[x+1/x-1]-(3)/(x-2)
Multiply by (x-1/x-1) to get
x+1 - 3(x-1)
----------- <- over (fraction)
(x-2)(x-1)
<<
x+1-3
---------- <- Over (fraction)
(x-2)
<<
x-2
-----
x-2

equals ONE!!
 
Last edited:

Answers and Replies

  • #2
1,425
1
Are you familiar with l'Hôpital's rule?
 
Last edited:
  • #3
58
0
No I am not
 
  • #4
Dick
Science Advisor
Homework Helper
26,258
618
Check your algebra going from the first 'over (fraction)' to the second one. You somehow made x-1 'disappear' through use of bad algebra. Simplify the numerator in the first expression.
 
  • #5
58
0
Thats okay i know what to do know, 3x divided by x is 2x
 
  • #6
Dick
Science Advisor
Homework Helper
26,258
618
Thats okay i know what to do know, 3x divided by x is 2x
3x MINUS x is 2x. 3x divided by x is 3. Are you sure you know what to do?
 
  • #7
58
0
well forget about it i got a tutor now
 
  • #8
Dick
Science Advisor
Homework Helper
26,258
618
Good luck!
 
  • #9
1,425
1
Meh, IMO, a tutor can only have a negative impact.
 
  • #10
Gib Z
Homework Helper
3,346
5
How do we have a better impact than a tutor :S
 
  • #11
1,425
1
We don't but it doesn't exclude the fact that a tutor doesn't, IMO.
 
  • #12
286
0
How do we have a better impact than a tutor :S
Because we're doing it because we love mathematics and enjoy helping others. The tutor is doing it to make money, or because it's a required work-study job. :tongue2:
 
  • #13
Gib Z
Homework Helper
3,346
5
Lol Thats a good point, the only reason we would even be helping is because we want to, and because of that we put in our best effort. But id rather be half-assed AND get paid! :P
 
Top