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sawq

  • one year ago

Urgent! Will fan and medal!! x + y = 27 4x + 1y = 45 Whats the solution to the equations and how did u get it? I know about substitution and elimination but its not working out... Help...??

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  1. pooja195
    • one year ago
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    What would you like to use?

  2. pooja195
    • one year ago
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    I suggest elmination

  3. sawq
    • one year ago
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    Ok elimination then

  4. pooja195
    • one year ago
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    Keep this in mind: OPPOSITES CANCEL whats the opposite of 4 ?

  5. sawq
    • one year ago
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    -4

  6. UsukiDoll
    • one year ago
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    I second elimination method.. works best.

  7. pooja195
    • one year ago
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    \[-4(-x + y = 27)\] distribute

  8. sawq
    • one year ago
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    4x + -4y = 27 ?

  9. UsukiDoll
    • one year ago
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    close but you forgot to distribute the -4 to the 27 what's -4 x 27?

  10. pooja195
    • one year ago
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    i accidently slipped in the -

  11. pooja195
    • one year ago
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    -4(x + y = 27) -4 * x = ? -4 * y = ? -4 * 27= ?

  12. sawq
    • one year ago
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    -108

  13. UsukiDoll
    • one year ago
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    we are distributing the -4 all over the first equation.

  14. UsukiDoll
    • one year ago
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    and yes -4 x 27 is -108 :)

  15. sawq
    • one year ago
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    -4x -4y -108

  16. UsukiDoll
    • one year ago
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    correct so your new first equation is -4x-4y=-108

  17. pooja195
    • one year ago
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    ill let doll finish :)

  18. UsukiDoll
    • one year ago
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    so now we have -4x-4y=-108 4x + 1y = 45

  19. UsukiDoll
    • one year ago
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    what do we need to do to get rid of the x?

  20. sawq
    • one year ago
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    lol @pooja195 thanks for ur help

  21. sawq
    • one year ago
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    inverse? @UsukiDoll

  22. UsukiDoll
    • one year ago
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    umm .. not quite.. our goal is to eliminate a variable.

  23. UsukiDoll
    • one year ago
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    -4x-4y=-108 4x + 1y = 45 so what do we need to do to get rid of this x?? we have -4x and 4x... maybe adding these equations together might work

  24. sawq
    • one year ago
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    ooh right so it would be: x - 5y = -63?

  25. UsukiDoll
    • one year ago
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    hmm .... only the right hand side of the equation is correct

  26. UsukiDoll
    • one year ago
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    ok... let's think finance for a bit you bought pens for $4, you paid $4 -4x+4x = ?

  27. sawq
    • one year ago
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    0x or just x

  28. UsukiDoll
    • one year ago
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    0x is fine... but 0 times x => 0

  29. sawq
    • one year ago
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    ohhhh

  30. UsukiDoll
    • one year ago
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    ok so we got rid of the x... now for the y we have -4y+1 it's like you are trying to buy pens for $4, but all you have is a dollar. How much more money do you need?

  31. UsukiDoll
    • one year ago
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    oops I meant -4y+1y

  32. sawq
    • one year ago
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    3 dollars

  33. sawq
    • one year ago
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    so -3y

  34. UsukiDoll
    • one year ago
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    yes! so -4y+y = -3y

  35. UsukiDoll
    • one year ago
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    so now we have -3y=-63

  36. UsukiDoll
    • one year ago
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    all we need to do is isolate y ... how do we do that?

  37. UsukiDoll
    • one year ago
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    in other words... we need y by itself.. no numbers no variables..

  38. sawq
    • one year ago
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    divide -63/-3=21

  39. UsukiDoll
    • one year ago
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    mhm so y = 21

  40. UsukiDoll
    • one year ago
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    the second part is finding x.. luckily it's easier.. we just need to subsitute y = 21 in one of the original equations. I highly suggest the easier ones

  41. UsukiDoll
    • one year ago
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    x + y = 27

  42. sawq
    • one year ago
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    ok: x + 21 = 27 x= 6

  43. UsukiDoll
    • one year ago
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    yes

  44. UsukiDoll
    • one year ago
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    so x =6 and y =21, but do these values work for the other equation. I know it does for the first equation because x+y=27 6+21=27 27=27

  45. UsukiDoll
    • one year ago
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    4x + 1y = 45 so plug in x = 6 and y =21

  46. sawq
    • one year ago
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    4*6=24 1*21=21 21+24=45!!!

  47. UsukiDoll
    • one year ago
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    yes 21+24=45 45=45 so we have found our x and y values.

  48. UsukiDoll
    • one year ago
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    alternatively you can choose to eliminate the y first and solve for x

  49. UsukiDoll
    • one year ago
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    x + y = 27 4x + 1y = 45 -x-y=-27 4x+y=45 3x = 18 x=6 6 + y = 27 -6 -6 y=21

  50. UsukiDoll
    • one year ago
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    ^_^ I got the same values by eliminating the y first and my steps were shorter too.

  51. sawq
    • one year ago
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    Thanks a million @UsukiDoll you are the best!!!!! you really helped me

  52. UsukiDoll
    • one year ago
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    I've noticed that through inspection I had two one y's so I figured if I make one of the y's negative I can solve this quickly.

  53. UsukiDoll
    • one year ago
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    :D you're welcome

  54. sawq
    • one year ago
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    gnite tysm

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