Lec 13 | MIT 18.03 Differential Equations, Spring 2006

[SeritaCruzxq237]

also ich bin blond

[agapitoflores001]

Equations make me dizzy. Hahahah

[RinaldiMeteoric]

Which lesson should I watch to learn how to "complexfy" as the professor does at 17:58. Thank you very much.

[FariFure]

@RinaldiMeteoric It's the 6th. And by the way, you're the laziest folk i've ever seen !

[h0wud0in2]

can someone tell me if that is first or second semster or whatever..?

[Liaomiao]

woot he's wearing my favorite jacket again!!!

[nepsjg]

the only reason i clicked on like on this video is when he mention it wants to be T but i make it X . lol funny. he is funny teacher.

[kaugith]

@farzadaf No, +sin is correct. If you expand out the terms (1+i)(cos x + i*sin x), you get (cos x - sin x) + i*(cos x + sin x). The particular solution takes only the imaginary part, the term (cos x + sin x), discarding the real part (cos x - sin x).

This is because the original ODE (y) became the imaginary part of the "complexified" ODE (y-tilde).

[longshot1710]

savior during finals

[gorgolyt]

23:40 should be -sin i think

[farzadaf]

@gorgolyt

yes I got -sin(x) as well

[mdfu1]

@gorgolyt No, he has it right. We want the imaginary part, aka the part with factor i.

The imaginary part of (1+i)(cos(x) + i sin(x)) is cos(x) + sin(x).

If we were looking for the real part, then indeed it would be cos(x) - sin(x).

[pmshadow]

he has a great sense of humor.

A huge thank you from Brazil.

[Gurrataxxx]

Exelente!. Gracias, desde Perú.

[eordano]

Buenísimo. Gracias, también desde Argentina

[GirlyVoice]

Why is it that we can assume 'a' to be a root of p(D) in general?

[gorgolyt]

@GirlyVoice it isn't. p(a) is normally nonzero, so a isn't a root. he covers the special case of when it is a root in the second half of the video.

[rambutanic]

)) Preps are all around vwry much alike. I had almost the same one of Physics ))

[danielk320]

gracias de verdad uy este tipo es lo maximo jeje explica muy bien!!!

[bellinivernon]

Muy lindo ! Gracias ,desde argentina.