Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

raebaby420

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

  • one year ago
  • one year ago

  • This Question is Closed
  1. Zelda
    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?

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

    Yes

    • one year ago
  3. Zelda
    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

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

    With me so far?

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

    Yes kinda

    • one year ago
  6. Zelda
    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.

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

    Im not sure

    • one year ago
  8. Zelda
    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)

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

    I got it! thanks!!

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

    No problem kiddo.

    • one year ago
    • Attachments:

See more questions >>>

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.