calculus help, please?

[Clip]

hey all,

trying to figure out something using limits and continuity.

i have tried almost everything, but cannot understand how limits and all relate to this problem

directions - prove that the equation has at least 1 real root

e^x = 2 - x

can anyone get me started on this?

 

[swaq]

Do you not have a 'y' variable?

 

[Clip]

y variable should be 0 if im trying to find a root, shouldnt it?

 

[swaq]

Yes, but I don't see a y in there... Are you sure you didn't mean "e^y = 2 - x" ?

 

[Clip]

positive

 

[swaq]

Then either I don't understand the problem correctly or it doesn't have a real root.

 

[da89soup]

First the whole baloon in space and now Math???? Come on we drive Supra's!!! They are cars that blow up and we love them..........were not rocket scientists here...................................lol

Whats next speling!!!!!!!

 

[Clip]

its got a real root, when you switch it all around to = 0

comes to e^x + x - 2 = 0, crosses at x ~ .44

soup, thanks for the words of wisdom but i need calculus in order to fund my builds later in life.

 

[jmanbball]

both y=e^x and y=2-x are continuous from neg infinity to infinity. As e^x approaches neg infinity it equals 1, and as 2-x aproaches neg infinity it equals infinity. As e^x approaches infinity it equals infinity, and as 2-x goes toward infinity it equals negative infinity. Therefore they must cross at some point, therefore being equal. Hope that helps

Georgia Tech is FTW!!

 

[suprasport91]

just got back from a lecture, but it seems you got what you needed

 

[swaq]

Oh right, duh, it's been too long since I've done lower level math. It's almost like the high levels are easier in some ways...

So what I think you want to do is find the limit as X approaches ~0.44 from the left and from the right. If you can show that e^x + x - 2 < 0 on one side of it and > 0 on the other side then you've just shown that the function must cross the x-axis, therefore it must have a root. Assuming the function is continuous.

 

[Clip]

thanks for the help, its still a mystery to me. im calling it a night and ill just ask the teacher tomorrow.

 

[suprasport91]

that was impled with him crossing x, i thought that was understood , anyhow im not a math major or anything, im more a LS, Chem guy, but ive taken my share of math, didnt like it, but i did it, which reminded me...when i first went to a linear algebra class two years ago i thought it was funny, my proff was like this class is about straight algebra...so everyone thought it was gonna be extremely simple, no quadratic anything just straight lines, I HATED that class, anyways i guess im just ranting

 

[swaq]

that was impled with him crossing x, i thought that was understood , anyhow im not a math major or anything, im more a LS, Chem guy, but ive taken my share of math, didnt like it, but i did it, which reminded me...when i first went to a linear algebra class two years ago i thought it was funny, my proff was like this class is about straight algebra...so everyone thought it was gonna be extremely simple, no quadratic anything just straight lines, I HATED that class, anyways i guess im just ranting

Linear algebra is more about matrices, eigenvalues, etc. You must have not got a very good prof or something because I really liked that class and it wasn't very hard (most the people in it got A's, I think). My plan is to take Linear Algebra II next term. Hopefully I won't have forgotten everything...

 

[jmanbball]

I'm taking linear algebra right now, pretty interesting stuff.

 

[suprasport91]

THis got me thinking we should have a homework helping thread, like a tutoring thread, it would probably be beneficial, doenst matter the level, ill be beginging my masters progam in about a year so i should be able to help out all high school and undergrad level courses, unless its somethin gfunky like art history...cant help you there, but im sure we can get a group assembled willing to help edit papers, hel pwith math chem and other subjects

Maybe? just a thought

 

[suprasport91]

I'm taking linear algebra right now, pretty interesting stuff.

i hated it...sorry couldnt stand it

well i dotn like math in particular to begin with, but i was fresh out of diff eqs and needed it was the last math requirement for my major, maybe my hatred was towards math in general

 

[Clip]

THis got me thinking we should have a homework helping thread, like a tutoring thread, it would probably be beneficial, doenst matter the level, ill be beginging my masters progam in about a year so i should be able to help out all high school and undergrad level courses, unless its somethin gfunky like art history...cant help you there, but im sure we can get a group assembled willing to help edit papers, hel pwith math chem and other subjects

Maybe? just a thought

thumbs up, but itd have to be heavily moderated so kids dont just come in and ask for answers...more like hints or ways to start the problem, and a way to check for accuracy.

 

[americanjebus]

thumbs up, but itd have to be heavily moderated so kids dont just come in and ask for answers...more like hints or ways to start the problem, and a way to check for accuracy.

x2 man

transfering into a mechanical engineering program and i know these sort of things are going to pop up again, i geuss we're just nerds with different channels of expression... engines.

 

[Clip]

yeah im gonna try for virginia tech's engineering program. gotta get through ap calc this year though, its gonna be killer. im glad that the community is here with the knowledge to help (if you guys dont mind me asking for it) and care enough to devote some time to this.

thanks all!