Login

Search the forums now!

Welcome, Guest. Please login or register.

October 01, 2025, 12:05:54 am
Pages: [1]   Go Down

Author Topic: Implicit diff discrepancies  (Read 677 times)  Share 

0 Members and 1 Guest are viewing this topic.

Chavi

  • sober since 1992
  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1413
  • "Death to the juice"
  • Respect: +5
Implicit diff discrepancies
« on: September 28, 2010, 11:23:42 pm »
0
Hey, whenever I come across a relation f(x,y) involving logs, I will always arrive at a different derivative depending on how I re-arrange the equation. Why is this so, and what mistake am I making?
For example:

"Find the gradient to the function at the point where "


When x = 1, y=e

Option 1


P (1,e)


Option 2
Rearranging gives:





According to the answers, option 2 is incorrect. Why is this so?
Logged
2009: Math Methods CAS [48]
2010: English [47]|Specialist Maths[44]|Physics[42]|Hebrew[37]|Accounting[48]  atar: 99.80
My blog: http://diasporism.wordpress.com/

98.40_for_sure

  • vtec's kickin in yo!
  • Victorian
  • ATAR Notes Superstar
  • ******
  • Posts: 2589
  • Respect: +10
Re: Implicit diff discrepancies
« Reply #1 on: September 28, 2010, 11:32:17 pm »
0
Because differentiaing 3/x is not 3lnx
Logged
2009: Texts & Traditions (28)
2010: English (45), Chemistry (40), Methods CAS (43), Specialist Maths (42)
ATAR: 98.40

Booksale: http://vce.atarnotes.com/forum/index.php/topic,33456.0.html
MM & SM tuition: http://vce.atarnotes.com/forum/index.php/topic,33942.0.html

Chavi

  • sober since 1992
  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1413
  • "Death to the juice"
  • Respect: +5
Re: Implicit diff discrepancies
« Reply #2 on: September 28, 2010, 11:46:08 pm »
0
Quote from: 99.95_for_sure on September 28, 2010, 11:32:17 pm
Because differentiaing 3/x is not 3lnx
FML
Logged
2009: Math Methods CAS [48]
2010: English [47]|Specialist Maths[44]|Physics[42]|Hebrew[37]|Accounting[48]  atar: 99.80
My blog: http://diasporism.wordpress.com/

sajib_mostofa

  • Victorian
  • Forum Leader
  • ****
  • Posts: 829
  • Respect: +6
Re: Implicit diff discrepancies
« Reply #3 on: September 29, 2010, 12:01:17 am »
0
How is option 2 correct if he has differentiated incorrectly?
Logged

m@tty

  • Victorian
  • ATAR Notes Legend
  • *******
  • Posts: 4324
  • Respect: +33
  • School: Heatherton Christian College
  • School Grad Year: 2010
Re: Implicit diff discrepancies
« Reply #4 on: September 29, 2010, 12:26:55 am »
0
Quote from: sajib_mostofa on September 29, 2010, 12:01:17 am
How is option 2 correct if he has differentiated incorrectly?

It isn't...
Logged
2009/2010: Mathematical Methods(non-CAS) ; Business Management | English ; Literature - Physics ; Chemistry - Specialist Mathematics ; MUEP Maths

96.85

2011-2015: Bachelor of Aerospace Engineering and Bachelor of Science, Monash University

2015-____: To infinity and beyond.

sajib_mostofa

  • Victorian
  • Forum Leader
  • ****
  • Posts: 829
  • Respect: +6
Re: Implicit diff discrepancies
« Reply #5 on: September 29, 2010, 01:21:35 am »
0
My bad, I read it incorrectly.
Logged
Pages: [1]   Go Up