Quantcast

A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

raebaby420

  • 2 years ago

Use the substitution method to solve the following system of equations. x + 2y – z = 7 4x – y + 3z = –2 2x + 2y – z = 9

  • This Question is Closed
  1. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Well, here we go: First let's set the first equation equal to: – z = 7 - x - 2y Which becomes: z = x+2y - 7 okay?

  2. raebaby420
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes

  3. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    No put this in equation #2: 4x – y + 3z = –2 Becomes: 4x – y + 3(x+2y - 7) = –2 Which becomes: 4x - y +3x +2y -21 = -2

  4. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    With me so far?

  5. raebaby420
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes kinda

  6. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    So, then we combine like terms to get: 4x - y +3x +2y -21 = -2 7x + y -21 = -2 y = -7x +19 And finally put this in the third equation and solve for x. So put in the first and second equations into the third one and solve for x.

  7. raebaby420
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Im not sure

  8. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    So we have z = x+2y - 7 and we have y = -7x +19 SO in the third equation: 2x + 2y – z = 9 Wherver you see a z, put that equation, and where you see a y, put in the equation for y. (First put in the y in the z equation)

  9. raebaby420
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I got it! thanks!!

  10. Zelda
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    No problem kiddo.

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

    • Attachments:

Ask your own question

Sign Up
Find 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
  • 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.