MAT244-2013S > MidTerm

MT Problem 3

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Patrick Guo:
Just got my midterm back on Friday and looked carefully through..


In the official 2013Midterm answers (both versions on Forum and on CourseSite), why we, when using variation-method, have
   v1 = - ∫ (t^2 + 1) g(t) / Wronskian  dt   ??  what is (t^2 +1) ?! Should that not be y2 = t^2 ?!

And how do we, from this step, get the next step, where (t^2 +1) changes to t with no reason ?

I see the results of v1 and v2 are correct, but the steps are totally incomprehensible and WRONG.

And why Wronskian = -t^2 ? should it not be t^2 ?

Victor Ivrii:

--- Quote from: Patrick Guo on March 16, 2013, 12:51:20 PM ---Just got my midterm back on Friday and looked carefully through..


In the official 2013Midterm answers (both versions on Forum and on CourseSite), why we, when using variation-method, have
   v1 = - ∫ (t^2 + 1) g(t) / Wronskian  dt   ??  what is (t^2 +1) ?! Should that not be y2 = t^2 ?!

And how do we, from this step, get the next step, where (t^2 +1) changes to t with no reason ?

I see the results of v1 and v2 are correct, but the steps are totally incomprehensible and WRONG.

And why Wronskian = -t^2 ? should it not be t^2 ?

--- End quote ---

Rats! The answer is simple: typo by the person who typed and the lack of proofreading (all instructors were busy preparing Final and TT2). Thanks! Fixed in all three instances (including on BlackBoard)

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