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EmmaH

  • one year ago

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....

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  1. ayushprasad
    • one year ago
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    |dw:1356562594798:dw|

  2. seidi.yamauti
    • one year ago
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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

  3. EmmaH
    • one year ago
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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

  4. seidi.yamauti
    • one year ago
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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

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

  6. seidi.yamauti
    • one year ago
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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

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

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

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

  10. EmmaH
    • one year ago
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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

  11. seidi.yamauti
    • one year ago
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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

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

  13. seidi.yamauti
    • one year ago
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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

  14. taylorstenger
    • one year ago
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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 ;-)

  15. EmmaH
    • one year ago
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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

  16. seidi.yamauti
    • one year ago
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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

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

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

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

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

  21. seidi.yamauti
    • one year ago
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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

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

  23. EmmaH
    • one year ago
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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

  24. EmmaH
    • one year ago
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    what next?

  25. seidi.yamauti
    • one year ago
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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?

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

  27. seidi.yamauti
    • one year ago
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    yes!

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

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

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

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

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

  33. EmmaH
    • one year ago
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    XD

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

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

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

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

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

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