When I first encountered Yahoo! Answers two years ago, I was impressed on how Yahoo! made such venue for Yahoo! users to exchange information via a "question and answer" format. When the answers come in, the asker can choose among all the answers as the "best" answer. The users then accumulate points for every question they post or they answer. The users can also help other users who are in dire need of quick information, especially those who ask problems in the "Science and Mathematics" section.
The catch in Yahoo! Answers is this: if the question is not resolved by the asker at a specified time frame, the users will actually VOTE for what they perceive as the "best" answer to the asker's question. It may seem that this system is placed because the voters are INTELLIGENT enough to choose the BEST answer... Unfortunately, it's NOT always the case....
For your information,I was actually a "victim" of a "best answer" to my question! To test how users (intelligently) answer questions in the "Science and Mathematics" section, I posted this question:
| | In evaluating limits, why is 1 raised to infinity considered an indeterminate form? |
(I was actually teaching Math 53 then and our topic was L'Hopital's Rule). I totally forgot about the "time limit", so when I checked out the "answers" to my question the users already voted for the BEST answer - from a user named "samk". And lo and behold, this is the BEST answer:
Best Answer - Chosen by Voters
Who says it's "indeterminate form"?
lim 1^x = 1
x->infinity
lim 1^x = 1
x->infinity
50% 3 Votes
Gyabo! WHAT KIND OF BEST ANSWER IS THIS??!! And it got just 3 votes! OMGWTF (sorry, I don't usually belt out and spell out swear words even in blogs). I actually read two very good answers - they even gave explanations and their sources! But, why did they vote for samk's answer????
This is not just my bad experience in Yahoo! Answers. I actually posted an answer - with explanations, sources, and all - to this question posted by a certain "Carbonbased Lifeform":
Anyone good at symbolic differential equations?
Can anyone solve this?
Obtain the solution of the differential equation
dx/dt+ax=A*sin(w*t) x(0)=b
I need the solution in the next 2 hours please.
Obtain the solution of the differential equation
dx/dt+ax=A*sin(w*t) x(0)=b
I need the solution in the next 2 hours please.
Additional Details
2 years ago
The x(0)=b is the initial condition, not part of the equation. I should have put some more spaces in there.
I refreshed my Math 65 memory a bit and did some research, and came up with this answer:
If a and w are constants, the equation dx/dt + ax = A*sin(w*t) is a linear first order differential equation, and you should use an INTEGRATING FACTOR e^v, where v = integral of a dt = at (dropping the arbitrary constant)
Hence, the left side of the equation becomes
d/dt(e^v * x) = e^v*(A*sin(w*t)) or d/dt(e^(at)*x) = e^(at) A*sin(w*t)
and integrating both sides of the above equation yields
x = e^(-at) * integral of [e^(at)*A*sin(w*t)] dt. You can do the integration, for sure. After which, you solve for the arbitrary constant C by invoking the initial condition x(0) = b.
I hope I have helped you even a bit with my answer :)
Hence, the left side of the equation becomes
d/dt(e^v * x) = e^v*(A*sin(w*t)) or d/dt(e^(at)*x) = e^(at) A*sin(w*t)
and integrating both sides of the above equation yields
x = e^(-at) * integral of [e^(at)*A*sin(w*t)] dt. You can do the integration, for sure. After which, you solve for the arbitrary constant C by invoking the initial condition x(0) = b.
I hope I have helped you even a bit with my answer :)
Source(s):
(1) Elementary Differential Equations by Rainville
(2) http://mathworld.wolfram.com/Integrating...
(2) http://mathworld.wolfram.com/Integrating...
Well, I left some details so that the user can exercise his brain cells a bit, but I think my answer is okay. But again, a stupid person (codenamed "JimmyR.com") actually got the BEST answer. And the answer is:
Best Answer - Chosen by Voters
dx/dt+ax=b :P
mathematica had some online find-the-derivitive program, last I remember
mathematica had some online find-the-derivitive program, last I remember
Mukyaa! >__< What irritated me more is that it only got ONE vote - and I presume it came from the USER who gave the answer! I just hope Carbonbased Lifeform bothered to read my answer and just forgot the time limit just like me....
I also read some questions and answers in that same category. To my dismay, what happened to me also happens to other askers as well: the stupid persons get to vote for the BEST answer given by another idiot like them.
Because of that, my belief of having intelligent users in Yahoo! Answers is already shattered to bits. It might not be worth my time visiting the site....
Now, If you don't know what the heck is Yahoo! Answers, go to http://answers.yahoo.com and ask, answer, and discover for yourself how stupid some users can get :p
P.S. Before I vented my ire via this blog, I actually answered two problems posted by users: the integral of 1/1 + cos x and solving for 'a' in the literal equation a^3g^12=at^4/b^2. My enthusiasm just got doused when I read those two "horrific" entries again... and I expect that the baka bunch in Yahoo! Answers will choose the most baka answers in the questions I answered. Sheesh >__<
