# Thread: Differential Equations - I need Help

1. ## Differential Equations - No more help, I FIGURED OUT THE MISTAKES WOOH

Okay here's a few problems that i've solved, i just need some math wiz to check me on my work. Thanks a lot guys, i really appreciate it!

1. y''' - 4y'' + y' + 6y =0
ANSWER: y=(c1)e^(3X) + (c2)e^(2X) + (c3)e^(-X)

2. 4y''' + 28'' + 61y' + 37y =0
ANSWER: y=(c1)e^(-X) + (c2)e^(-3X)(cos0.5X) + (c3)e^(-3X)(sin0.5X)

3.y'''' - 2y''' + 2y'' -2y' + y =0
ANSWER: y=((c1) + c(2)X)e^X + (c3)e^X(cosX) + (c4)e^X(sinX)

4. 4y''''' - 23 y'''' -33y'' - 17y' - 3y =0
ANSWER: y=(c1)e^(3X) + ((c2) + (c3)X)e^(-X) + ((c4) + (c5)X)e^(-0.5X)

FOR # 5/6 I USED METHOD OF UNDETERMINED COEFIFICENTS FOR NONHOMOGENEOUS DIFF EQ'S

5.y'' - 3y' - 4y = 2sinX
ANSWER: y=(c1)e^(4X) + (c2)e^(-X) + (3/17)cosX - (5/17)sinX

6.y'' - 3y' -4y = 4X^2
ANSWER: y= (c1)e^(4X) + (c2)e^(-X) - (1/8) - (1/4)X^2

2. I hope i never have to do math that hard...

3. >>I hope i never have to do math that hard...

well if you are going into ANY engineering field you will have to leardn DFQ. KneeGrow, I'll check it out later tonite if I get some spare time.

4. -DAAWEETED!!!!!!-

5. You are a loser.

6. huh? what'd i do now?
EDIT
alright i get it..
..i guess ill delete it

7. I obviously missed something

8. Ahh someone please check those answers the first four are so easy just check for the roots then do e^x but i need someone to check 5 + 6

Thanks a lot

9. agh.... type in sentences please

I only WISH i could do those problems. I guess you just aren't an english person.

[half j/k]
And, also, your cheap attempt at making it look like you have 4000 something posts is, at the very least, laughable and embarassing. Embarassing not only to you, but to all of mankind (for harboring such rabid stupidity!).
[/half j/k]

10. Okay whatever ya'll can stop posting on this thread as i have figured out all the answers Thanks to all that helped = 0 people lol? Anyways whatever