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icalibear

  • one year ago

How to solve systems with elimination? 5x - 2y = 28 -20x + 8y = -100 I know that if there are two of the same variable then they cancel and then it is easy to solve when you add the equations together, but what if neither equation has corresponding variables???

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  1. anonymous
    • one year ago
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    you have to make them become corresponding 5x-2y= 28 (multiply by 8 ) = 80x-16y =224

  2. icalibear
    • one year ago
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    How are those corresponding :s

  3. anonymous
    • one year ago
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    and you have to make this for the second one -20x +8y=-100 (muliply by 2) = -40x +16y = -200 and solve by elimination now

  4. anonymous
    • one year ago
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    eliminate 16y

  5. icalibear
    • one year ago
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    why did you multoply by 8 and 2 sorry

  6. UsukiDoll
    • one year ago
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    If I was given that problem I would eliminate x... seems easier if I distribute the 4 all over the first equation

  7. UsukiDoll
    • one year ago
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    and for that reason. I have to distribute the 4 all over the first equation because I want to eliminate a variable and solve for the other. In this case, 4(5x-2y=28) 20x-8y=112 (this is my new first equation) so I add my new first equation to the second equation so I can get rid of the x

  8. anonymous
    • one year ago
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    to make them corresponding...

  9. anonymous
    • one year ago
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    @Michele_Laino please help

  10. icalibear
    • one year ago
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    i got 3/5...

  11. UsukiDoll
    • one year ago
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    oh geez we are forced to take the y's out and then solve for x because by distributing the 4 all over the first equation, I ended up destroying x and y., and we don't want that.

  12. UsukiDoll
    • one year ago
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    \[8(5x-2y=28)\] \[2(-20x+8y=-100)\] \[40x-16y=224\] \[-40x+16y=-200\] HUH? Am I reading this wrong? even I got the same problem.

  13. anonymous
    • one year ago
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    i was right @icalibear

  14. icalibear
    • one year ago
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    |dw:1434862139806:dw|

  15. icalibear
    • one year ago
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    i meant to type 40x

  16. icalibear
    • one year ago
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    sorry! typo

  17. icalibear
    • one year ago
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    i will fix this

  18. UsukiDoll
    • one year ago
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    we are supposed to distribute 8 and 2 THROUGHOUT THE equation. We can't have it one sided

  19. icalibear
    • one year ago
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    |dw:1434862362988:dw|

  20. UsukiDoll
    • one year ago
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    your x portion is off and when you fix it... x and y will cancel

  21. anonymous
    • one year ago
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    i made a mistake on the multiplication.. sorry

  22. hartnn
    • one year ago
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    40x - 40x = 0 -16y +16y = 0 224 -200 =24 so you get 0 = 24 in the end. Is that even possible?

  23. icalibear
    • one year ago
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    is there even a solution if both x and y cancel because that leaves nothing

  24. UsukiDoll
    • one year ago
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    it's an inconsistent system which leads to no solutions at all

  25. hartnn
    • one year ago
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    0 =24 true or false?

  26. icalibear
    • one year ago
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    false..

  27. icalibear
    • one year ago
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    so there is no solution

  28. hartnn
    • one year ago
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    right, so there is NO value of x or y which can satisfy those 2 equations. correct, no solution!

  29. icalibear
    • one year ago
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    okay

  30. icalibear
    • one year ago
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    thanks so much guys.. i do not remember this from 9th grade..

  31. UsukiDoll
    • one year ago
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    yeah. I did it both ways... when I tried to eliminate x and I ended up with x and y going away similarly when I tried to eliminate y, I ended up and x and y going away as well leaving me with both situations having LHS doesn't equal the RHS left hand side doesn't equation the right hand side.

  32. icalibear
    • one year ago
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    okay

  33. UsukiDoll
    • one year ago
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    but I still would've done the x first... multiply that first equation by 4 makes it faster to get to the conclusion

  34. UsukiDoll
    • one year ago
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    \[4(5x-2y=28)\] \[-20x+8y=-100\] \[20x-8y=112\] \[-20x+8y=-100\] adding these two equations forces x and y to disappear.

  35. icalibear
    • one year ago
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    I have one more..

  36. icalibear
    • one year ago
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    I multiplied to get the middle terms the same but then i got a fraction

  37. icalibear
    • one year ago
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    Nevermind made an error ! 6 x 3 is 18

  38. icalibear
    • one year ago
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    |dw:1434862940828:dw|

  39. icalibear
    • one year ago
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    is this set up right

  40. hartnn
    • one year ago
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    yes!

  41. UsukiDoll
    • one year ago
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    yes it is.

  42. icalibear
    • one year ago
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    so x = 9

  43. hartnn
    • one year ago
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    yup

  44. icalibear
    • one year ago
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    okay

  45. hartnn
    • one year ago
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    y =.. ?

  46. UsukiDoll
    • one year ago
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    yay... that was fast x)

  47. hartnn
    • one year ago
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    yes, she got it, she is now unstoppable! ;)

  48. UsukiDoll
    • one year ago
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    :D

  49. icalibear
    • one year ago
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    I didnt need to find y for the question but i know you would substitute it back in

  50. icalibear
    • one year ago
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    thanks so much guys :)

  51. hartnn
    • one year ago
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    right, go ahead and find it...you're doing it to learn, right? not just for completing the homework...

  52. icalibear
    • one year ago
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    yes this is just practice

  53. UsukiDoll
    • one year ago
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    practice is fine....it's the questions with so many questions and multiple choices with omg this is due in an hour are frown upon on os

  54. icalibear
    • one year ago
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    this isnt a class i get credit for, its just summer prep so i can get into math 128 in the fall

  55. icalibear
    • one year ago
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    ive graduated and I forgot every bit of this intermediate algebra!

  56. UsukiDoll
    • one year ago
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    actually... well in my textbook... this is elementary algebra 1

  57. icalibear
    • one year ago
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    either way, I need a refresher

  58. hartnn
    • one year ago
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    waiting for the y value :P

  59. icalibear
    • one year ago
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    sorry i have moved way on.. D:

  60. hartnn
    • one year ago
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    its ok ^_^ probably next time :)

  61. icalibear
    • one year ago
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    Yep

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