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EmmaH

PLEASE HELP!!!! Solve the system, using substitution. One point for correct steps, one point for correct ordered pair, (a,b). a + b = 4 and 2a + 3b = 11 i tried to solve for a but ended up with 1/-5 i dont think thats right....

  • one year ago
  • one year ago

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  1. ayushprasad
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    |dw:1356562594798:dw|

    • one year ago
  2. seidi.yamauti
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    a+b=4 2a+3b=11 a=4-b 2(4-b)+3b=11 (substituing a as found) a=4-b 8+b=11 a=4-b b=3 so, a=1 and b=3

    • one year ago
  3. EmmaH
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    a=4-b 2(4-b)+3b=11 i get that but how did ypu go from that to a=4-b 8+b=11

    • one year ago
  4. seidi.yamauti
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    you need first to isolate a or b in one of the equations, and use this on the other. I have skipped one or two steps, but if you do correctly, the answer (a,b)=(1,3) will be found

    • one year ago
  5. seidi.yamauti
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    2(4-b) = 8-2b, write it and keep solving

    • one year ago
  6. seidi.yamauti
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    This problem is about solving what is called 'linear system'. You have some equations with letters and need to find what are their values. Further you will see that not all of this kind of systems can be solved (when there are more letters than equations) - but you can just ignore it by now tell me when you're done, it just a matter of practice to solve it better an faster

    • one year ago
  7. EmmaH
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    ok question: in 2(4-b)+3b=11 would it equal 8-b+3b=11 or 8-2b+3b=11?

    • one year ago
  8. seidi.yamauti
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    8-2b+3b=11

    • one year ago
  9. seidi.yamauti
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    because the 2 multipies both 4 and -b in 2(4-b)

    • one year ago
  10. EmmaH
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    this is what i got 8-b+3b=11 8+2b=11 2b=11-8 2b=3 2b/2=3/2

    • one year ago
  11. seidi.yamauti
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    re-do it haha it is 8-2b+3b=11 but what you've done is right if it was 8-b+3b=11

    • one year ago
  12. taylorstenger
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    |dw:1356564451980:dw|

    • one year ago
  13. seidi.yamauti
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    kind of what taylor said... You need to do all by yourself, and just ask for some tips. Because it is when you think alone that you really understand. try and try and try. It's hard, but sometime there will be just the right answer

    • one year ago
  14. taylorstenger
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    Yup. U cant just go on the internet and find answers for everything and anything. Theres a reason its in ur text books, and theres a reason teachers teach it to u. If u paid attention, u wouldnt be askin questions on OpenStudy ;-)

    • one year ago
  15. EmmaH
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    im not trying to gte an easy answer i honestly dont understand this also i didnt respond bcs my inter net went out

    • one year ago
  16. seidi.yamauti
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    I was just complementing. Just to say, first step, you can ask a lot about your doubt, but with time, you will do it without any help. haha

    • one year ago
  17. EmmaH
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    im really confused about what to do after i get -2b=3 can you please continue to help me?

    • one year ago
  18. seidi.yamauti
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    i'm here. Let's see..

    • one year ago
  19. seidi.yamauti
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    where is -2b=3 ?

    • one year ago
  20. EmmaH
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    8-2b=11 -2b=11-8 -2b=3

    • one year ago
  21. seidi.yamauti
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    you have a+b=4 2a+3b=11 then, you use ANY of these equations to isolate a letter in the case, I've used the first and came up with a=4-b (so, from now on, that's what a is) you could also do it in the second, but that's too much work

    • one year ago
  22. seidi.yamauti
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    I isolated a, but it could be also b. both correct

    • one year ago
  23. EmmaH
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    thisd is what ive done a + b = 4 and 2a + 3b = 11 2(4-b)+3b=11 8-b+3b=11 8-2b=11 -2b=11-8 -2b=3

    • one year ago
  24. EmmaH
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    what next?

    • one year ago
  25. seidi.yamauti
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    2(4-b)+3b=11 8-b+3b=11 This is not right, because when you multiply a number times something in parenthesis, everything inside is multiplied so 2(4-b)+3b=11 what comes next?

    • one year ago
  26. EmmaH
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    8-2b+3b=11?

    • one year ago
  27. seidi.yamauti
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    yes!

    • one year ago
  28. seidi.yamauti
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    and i guess, if you go back to my first post, it will make more sense now

    • one year ago
  29. EmmaH
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    8-1b=11 -1b=11-8 -1b=3 -1b/-1=3/-1 b=-3 is that right

    • one year ago
  30. seidi.yamauti
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    nonononoooo you've got 8-2b+3b=11 which is equal to 8+b=11 not 8-b=11

    • one year ago
  31. EmmaH
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    8+b=11 b=3 ??

    • one year ago
  32. seidi.yamauti
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    YES! hahahaha

    • one year ago
  33. EmmaH
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    XD

    • one year ago
  34. EmmaH
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    (1,3) ?

    • one year ago
  35. seidi.yamauti
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    That's it :)

    • one year ago
  36. EmmaH
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    thank you for taking the time to help me!

    • one year ago
  37. seidi.yamauti
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    i've found the khan academy page on algebra. https://www.khanacademy.org/math/algebra This may help you

    • one year ago
  38. seidi.yamauti
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    and you're welcome

    • one year ago
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