Incorrect answers to derivative of this equation?

[Steven G]

That is incorrect I provided the formula for what I used in the equation.



I clearly have it written have the equation on the right side of the paper. I ways always told by college math teachers, physics, chemistry to state the equation or law before performing it.

Equation used:

[MATH]ln(\dfrac{A}{B})=ln(A)-ln(B)[\MATH][/MATH]

Look from your 4th line to your 5th line. You factored out the 1/2 AND you used the non fact that ln( A) - ln(B) = ln (A-B).

 

[Steven G]

notation was missing.

[MATH]\frac{df}{dx}[/MATH] and [MATH]-\csc(x)[/MATH] and the student jumps a lot of steps between line 1 and line 2. It is clearly correct but doesn't describe when he is taking the derivative of the function in post #18

Jumo called out my answer as incorrect when it clearly is correct with minor flaws similar to how the student performed. I don't want to mislead the student.

You arrived at -csc which has no meaning at all from -sinx/cosx which is tan x. You also used ln's incorrectly. Sorry but these are not minor mistakes at all.

 

[BraveHeart258]

I jumped slightly jumped steps and you are correct but you are wrong about the equation which you made reference to:

[MATH]ln(dfrac{A}{B})=ln(A)-ln(B)[\MATH] I apologize for pushing you but its better that the student learned and corrected his by seeing my mistakes? I hope he didn't leave seeing that his problem is mostly solved. I think you are really intelligent I appreciate your feedback. Are you okay with me challenging you to understand the real answer for me and the student? Would you prefer I did this Jumo? as shown in the attachment:[/MATH]

 

[Steven G]

I jumped slightly jumped steps and you are correct but you are wrong about the equation which you made reference to:

[MATH]ln(dfrac{A}{B})=ln(A)-ln(B)[\MATH] I apologize for pushing you but its better that the student learned and corrected his by seeing my mistakes? I hope he didn't leave seeing that his problem is mostly solved. I think you are really intelligent I appreciate your feedback. Are you okay with me challenging you to understand the real answer for me and the student? Would you prefer I did this Jumo? as shown in the attachment:[/MATH]

In your attachment the right hand sides are all equal, the left hand sides are all equal but in all three lines you wrote the left hand side does NOT equal the right hand side. That is all three equations you wrote are wrong.

 

[BraveHeart258]

Okay I understand. the (1/2) must be taken out before you can use that formula because its stated in the formula

 

[Steven G]

Rule or special case Formula Product ln(xy)=ln(x)+ln(y)ln⁡(xy)=ln⁡(x)+ln⁡(y) Quotient ln(x/y)=ln(x)−ln(y) Log of power ln(xy)=yln(x)ln⁡(xy)=yln⁡(x) Log of ee ln(e)=1ln⁡(e)=1 Log of one ln(1)=0ln⁡(1)=0 Log reciprocal ln(1/x)=−ln(x)

I am still not following? Is this incorrect? ln(x/y)=ln(x)−ln(y)?

Yes, ln(x/y)=ln(x)−ln(y).

However your 1st equal sign is not valid in your attachment. Why would you think that ln(A/B) = ln(A^.5) - ln(B^.5)? Which property or properties that you listed shows that?

Also what does f( ) mean????

 

[BraveHeart258]

f(x)

 

[JeffM]

None of this is helping the original poster. Braveheart gave an answer, which is not what this forum is about. It is a help site rather than an answer site. Then there are errors in his work. Instead of fixing them so as not to confuse the student, he is arguing about them. I suggest he be banned. We do not need to have helpers' time wasted with such nonsense.

 

[lookagain]

None of this is helping the original poster. Braveheart gave an answer, which is not what this forum is about. It is a help site rather than an answer site. Then there are errors in his work. Instead of fixing them so as not to confuse the student, he is arguing about them. I suggest he be banned. We do not need to have helpers' time wasted with such nonsense.

I sent a conversation message to Subhotosh Khan asking to ban BraveHeart258
over his incompetence and doubling down about it, combined with giving a full solution with of such.
I referenced JeffM's recommendation. I also reported his first post in this thread
with the similar reasons.

 

[BraveHeart258]

Want me to stop? Help me find a job! I have medical bills, I am worried that I can't pay
I really want to only help people and love to share the world with others.

 

[lookagain]

Want me to stop? Help me find a job! I have medical bills, I am worried that I can't pay
I really want to only help people and love to share the world with others.

Yes, I would like you to ... * For one, on tutoring jobs, I (we) had to be proficient in
college algebra with a fair amount of first year calculus to start. In another we had
to be able to pass the college algebra portion of an Accuplacer Math Placement
Exam on a computer. I regularly administered that exam at that job for years as
well.

* have the forum users' interests at heart by being knowledgeable enough.

What is your plan/strategy to reduce your medical bills by writing solutions to
certain math problems on the Internet, specifically taking the time at this math
help site (or possibly others) and in a volunteer style?


I am not qualified to be giving out job counseling information to you.

 

[JeffM]

Want me to stop? Help me find a job! I have medical bills, I am worried that I can't pay
I really want to only help people and love to share the world with others.

I would like you to stop giving answers.

I would like you to take pains not to make blatant errors in what you present to students.

I would like you to at least acknowledge, and if possible to correct, the errors that, like all of us, you will inevitably make from time to time.

I would VERY MUCH like that you not insinuate that anyone needs to provide you a monetary benefit of any kind, let alone employment, before you will abide by the spirit of this site.