PeteB

I'm attempting to solve y'' + 2y' + 3y = 0 using series solutions. However, the recurrence relation I receive is c_{n} = (-(n+2)(n+1)c_{n+2} - 2(n+1)c_{n+1})/3

I'm not sure how to handle this when c_{n} is based on c_{n+2} and c_{n+1}. I know the solution is y = (c1)e^(-x)sin(sqrt(2)x) + (c2)e^(-x)cos(sqrt(2)x) using the roots (-1 +- sqrt(2)i). But how would I solve the recurrence relation?

I take the cosine of 7pi/2, and then the cosine of 35pi/10.

Why does it give me two different answers, is it broken? (7pi/2) (5/5) = 35pi/10 (Not reduced of course.)

It spits out 7E-13 and -3E-13... Which is pretty confusing to me because I think anyone knows that the cosine of 7pi/2 is zero right?

3pi means it lands on the x axis on the left side, cos(3pi) is -1. Add another pi/2 to get 7pi/2 and it should be zero... Right?

Just wondering if its really possible or not for my grandma, who is completely obsessed with spraying raid the moment she sees even a few ants in the kitchen, to be inadvertently poisoning me because of the vapors that bloody spray keeps giving off.

I always wake up with a nasty sore throat when she sprays the stuff and I can smell it even though she buys the odorless kind. I never want to eat anything kept open in the air in the kitchen after she's gone nuts spraying that stuff. Its terrible and I just want to know if I'm crazy or if its normal.

When over-sprayed, does raid give off harmful vapors? Or am I delusional? Perhaps I'm allergic to it?

I'm pretty sure most of you are familiar with that annoying high pitch sound that pervades the entire house when a problematic TV set is turned on, right?

Is it damaging to my hearing to be well, hearing that sound all day virtually every day because my family doesn't care to ever fix/replace any of their TV sets?

PS: Yes, I'm pretty sure its not Tinnitus... Though I may damned well be developing it because I still hear the sound for awhile after leaving the house. It eventually goes away but the moment I step close to another TV that's making that noise again... Ugh :(

One strange thing I've said before is I hear a similar sound when I press jawbone back. Maybe I have something weird going on with my TMJ or something that actually lets me do that but at least its voluntary. lol

Square root of a^2-x^2

x = a(sinT)

Something about a>0 and less sure but 1>(T) > 0 (?)

How exactly do I do this? It was on a trigonometry quiz I had today and I have the feeling I totally bombed on it. I could only go so far as remove the radical and write a-a(sinT)

My professor wanted it simplified further with identities but I was totally clueless. No doubt this is the quiz I'm dropping to make sure I get an A. ><;