Question

How do you solve these 2 equations:
u= 2x-3y
v= -x+y

Answer 1

hey @psymon! lol

Answer 2

Lol, heya there. Because of the variables.....this is a vector question? No idea, haha. Not enough context for me to have any idea what's going on o.o

Answer 3

lol my bad ill post the actual entire question in a pic

Answer 4

This is the question

Answer 5

This is the solution from the solutions manual

Answer 6

an this is how chegg decided to start off the problem differently

Answer 7

Gotcha. quite a bit ahead of what ive seen. I just bought a calc 3 text, so I bet I could look itup. Chegg?

Answer 8

yeah chegg is like a homework help site lol

Answer 9

how would u solve those 2 equations though

Answer 10

Ah, cool xD Well, I'll have to look it up, completely new to me. I just gotta find jacobian and stuff lik that in my textbook. Have you been to the lamar website? Professor who has all his class notes online?

Answer 11

yeah but i forgot to look around :S lol. Also my test is tomorrow... this is the very last section im cramming through right now. Not too smart..

Answer 12

Yeah, not good. And the funky greek symbol im not used to. That's for partial derivative, correct?

Answer 13

yes

Answer 14

I got through one of these problems already that is similar but i seem to be stuck on solving those 2 equations on this one idk why

Answer 15

Okay, yay, closer to making sense xD Alright, let's see what i can do with the first part.

Answer 16

by looking at the solution they go from 2x-3y = u and -x+y=v (which is given) to -x = u+3v and y = v+x. I feel like its something simple im missing

Answer 17

Im thinking some sort of substitution. Im hopping back and forth, so Ill be a bit slow. But I do wanna take a look at it.

Answer 18

np

Answer 19

Yeah, thats exactly what they did. they took -x + y = v and said y = v+x. Then they substituted that y value in for y in the second equation.

Answer 20

You kinda see how they got that? xD

Answer 21

Haha yeah I just worked it out doing what you said and got the -x = u +3v. im still not sure why they left it as -x. Would I then plug the -x into the 1st equation to get y = v+x

Answer 22

yeah, you would have to do another substitution. Use x = y-v and sub that into the 2x equation. You'll getthe other value you need :3

Answer 23

would u recommend using this substituion method or the chegg route

Answer 24

Substitution. More straightforward and probably more familiar to us, lol. I would have never tried anything like what Chegg did, although I can see why they did that.

Answer 25

substitution it is..lol.. I understand it a lot better thanks to you.

Answer 26

Glad that part works xD I'll work my way over to the jacobian part slowly, lol.

Answer 27

rofl ok. The determinant part is easy. b is eh im gonna try it now

Answer 28

Alright, Ill ignore that part then, unless its needed for part b xD Just havent been able to focus on it yet, lol.

Answer 29

Figure it out? :P

Answer 30

Yes just finished. Thanks so much! on to the next one -.-. on the bright side i've got about 4-5 problems left and then i can get a couple hours rest before my test lol

Answer 31

Lol, okay. Yeah, I figured it out, just had to make sure if you did, lol. Wasn;t that bad it seems O.o

Answer 32

Just a bunch of subbing xD

Answer 33

Lol yeah it was just the substitution that got me. I really shouldn't be struggling with that when I'm in cal 3.. .-.

Answer 34

Lol, hey, it happens. How was calc 1 and 2 for ya then?

Answer 35

cal 2 was hell for me lol. Cal 1 wasn't too bad. and Cal 3 would be easier if it wasn't only a month long haha

Answer 36

Yeah, thats the brutal part x_x I can't wait til I take it, but it was a schedule conflict D: I still bought the textbook for it to study, though. I gotta start from the beginning, though, haha. At least the first part is easy it seems. Calc 2 really helped out my overall calc skills xD

Answer 37

dude you'll be fine you've been helping me out with like everything lol

Answer 38

I just gotta study it first, haha. Atleast for my textbook, looks like youre at the end of chapter 14 and theres 16 chapters xD

Answer 39

haha im using the 12th edition of thomas calculus. this is chapter 15.8. We're starting and finishing 16 in like 1 day next week, then final like 2 days after >.<

Answer 40

Oh xD So howd you get the solution manual for it?

Answer 41

chegg has the solutions online and I also found a pdf with the solutions ;D

Answer 42

Wow, nice, haha. For me, the textbook I use has a website that does some minimal work for the odd numbered questions. Sometimes it helps a lot, sometimes not at all, but calculator + that works out. I just need to find out how to get my calculator to do more of the calc 3 stuff x_x

Answer 43

i have a browser with bookmarks dedicated to online calculators O.o lol

Answer 44

All of those work for this stuff? xD

Answer 45

not really rofl :(

Answer 46

Ah D: I think my calculator should be able to do some of it, I just need to learn how x-x

Answer 47

@Psymon Got an 80 on my test! Wooooo