A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
Systems of Equations, please help!!
anonymous
 one year ago
Systems of Equations, please help!!

This Question is Closed

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I know what the answers are but I cannot seem to get there =(

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Let's focus on #24 \[\Large \begin{cases} 13 = 3x  y\\ 4y3x+2z = 3\\ z = 2x  4y\\ \end{cases}\]

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Notice we have a pair of 'z's here \[\Large \begin{cases} 13 = 3x  y\\ 4y3x+2{\LARGE \color{red}{z}} = 3\\ {\LARGE \color{red}{z}} = 2x  4y\\ \end{cases}\]

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1what we can do is replace the 'z' in the second equation with '2x4y' since z = 2x4y in the third equation we can then drop the third equation after substitution \[\Large \begin{cases} 13 = 3x  y\\ 4y3x+2\color{red}{z} = 3\\ \color{red}{z} = 2x  4y\end{cases}\] \[\Large \begin{cases} 13 = 3x  y\\ 4y3x+2\color{red}{(2x4y)} = 3\end{cases}\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0For 24, which I think I maybe got right, I ended up with \[y=3x13, 4y3x+2z=3, z=2x4y\] and then substituted to end up with \[4(3x13)3x+2(2x4(3x13))=3\] which simplified to \[x=5, y=2, z=2\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Is that correct (I have all the work but it's so long so I didn't post it sorry)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1You did the right steps. Nice job

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Awesome, thanks! Um do you think you could help with 25,26,27,28, or 29?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Those are definitely harder because one variable isn't already isolated. But we can isolate a variable, say z if we pick on the third equation and solve for z, we get 3x  2y  z = 9 3x  2y  z+z = 9+z 3x  2y = 9+z 3x  2y + 9 = 9+z+9 3x  2y + 9 = z z = 3x  2y + 9

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1agreed so far?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Okay =) Yeah that looks good

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1once we have z isolated, we can replace every copy of `z` in the first two equations with `(3x  2y + 9)`

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1first equation: `x+3yz = 4` will turn into `x+3y(3x  2y + 9) = 4` second equation `2xy+2z=13` will turn into `2xy+2(3x  2y + 9) =13`

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1at this point, the 'z' has gone away leaving you with a system of 2 equations with 2 unknowns

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0That makes sense! I think I tried to overcomplicate it last time lol. So from here, you would just isolate a variable in one of them and then plug whatever that is into the other equation? Or would you solve both for a variable and then solve it like a regular system?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1you can use a number of methods to solve this new system 1) substitution 2) elimination 3) matrices 4) graphing graphing is probably the fastest way, but it doesn't always guarantee you get the exact answers (the point may have fractional coordinates)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I am most comfortable with substitution =) So I solve both for a variable (let's say y, so y=something) and then just substitute (if y=x and y=2 then 2=x)?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1you are correct

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1let me know what you get

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Awesome thanks! Alright I'll do that real quick...

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I got y=2x13 and y=(5/3)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1x,y, & z are all whole numbers for #25

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0True. And the answer for this is x=0, y=1, z=7... let's see what I did wrong.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ah. I combined x and y. I'll redo it

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1how did you get `y=2x13`? which equation did you solve for y?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I solved the first one to get that.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1442627727801:dw Here's what I did to solve the first eq.

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1You made a mistake in distributing x+3y(3x  2y + 9) = 4 turns into x+3y3x + 2y  9 = 4

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1notice the `+ 2y` and `  9`

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0OH! I was wondering about that. So the negative sign gets distributed!

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1yeah think of `(3x  2y + 9)` as `1*(3x  2y + 9)`

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1and that 1 multiplies with each term inside

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0All right =) Here, I'll try that again

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0and y=(8/5x)+1 for the other which when set equal to eachother make x=0 which is correct

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1I'm getting the same equations when I solve for y

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yay! When I plugged x=0 into the other eq.'s, it worked! Thank you so much!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I think I should be able to do the rest now. Thanks again =)
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.