A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • 5 years ago

Solve using the elimination method. If the system has an infinite number of solutions, use set builder notation to write the solution set. If the system has no solution, state this. x + 9y = 79 -7x + 9y = 23

  • This Question is Closed
  1. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    eliminate y's by multiplying first equation by -1

  2. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    -x - 9y = -79 would that be right for the first one?

  3. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    GREAT!

  4. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so you should get -8x=-56 right?

  5. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how do you get that?

  6. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so x=7 plug x into second eqn to get y

  7. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the ys cancel and you have -x + -8x and -79 + 23

  8. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sorry -x + -7x

  9. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh okay. so you use it to both equations after you solve the first one?

  10. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you can pick one equation to plug back into to get the other variable...preferably the one you didn't alter

  11. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    plug both x and y into both original equations to check

  12. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    -7-9(8)=-79 -7-72=-79 -79=-79 TRUE

  13. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    OK. So what do I do after I plug it into the second equation?

  14. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    -7(7)+9(8)=23 -49+72=23 23=23 TRUE

  15. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    solve for y then combine (x,y) for solution (7,8)

  16. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So, (7,8) would be the answer correct? That's what I got.

  17. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    GREAT!!!!!

  18. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you so much. How would I know if an equation has no solution or infinite solutions?

  19. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no solution would give you different numbers on each side of equal side such as -2=0 and infinite solutions would give you same number on each side like 5=5

  20. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    parallel lines have no solution and same line have infinite solutions so if you put them in y=mx+b form and look at slope (m)-same for parallel

  21. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok. thanks

  22. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    welcome...medal or fan me please :)

  23. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

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
  • 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.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.