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calculusxy

  • one year ago

Solving Systems of Equations by Substitution. 1. -3x + 3y = 4 -x + y = 3 2. -5x - 8y = 17 2x - 7y = -17

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  1. calculusxy
    • one year ago
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    @jim_thompson5910 @Nnesha

  2. calculusxy
    • one year ago
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    @mathstudent55

  3. calculusxy
    • one year ago
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    This is my work for question 1. we could figure out the value of y by: y = 3 + x -3x + 3(3 + x) = 4 is that correct?

  4. calculusxy
    • one year ago
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    i need to solve for x, which i know, but i just wanted to know whether my set up was fine or not.

  5. Nnesha
    • one year ago
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    yep yep right :=)

  6. calculusxy
    • one year ago
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    so then we can simply it to: -3x + 9 + 3x = 4

  7. Nnesha
    • one year ago
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    yep

  8. calculusxy
    • one year ago
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    but if we do -3x + 3x = 0x and I am not even sure if there is any such thing as 0x.

  9. Nnesha
    • one year ago
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    yes so they cancel out

  10. Nnesha
    • one year ago
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    thats mean no solution both sides are not equal \[9 \cancel =4\]

  11. calculusxy
    • one year ago
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    oh okay :)

  12. calculusxy
    • one year ago
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    and for the next one...

  13. Nnesha
    • one year ago
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    yep

  14. calculusxy
    • one year ago
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    we can figure out the value of x... 2x - 7y = -17 2x = -17 + 7y 2x / 2 = (-17 + 7x) / 2 x = -8.5 + 3.5x

  15. Nnesha
    • one year ago
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    hmm you mean x = -8.5 +3.5 y right ?

  16. calculusxy
    • one year ago
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    yes sorry :)

  17. Nnesha
    • one year ago
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    its okay yep right

  18. calculusxy
    • one year ago
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    -5(-8.5 + 3.5y) - 8y = 17

  19. calculusxy
    • one year ago
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    42.5 - 17.5y - 8y = 17 42.5 - 25.5y = 17 -25.5 - 25.5y = 17 -25.5y = 42.5 y = 1.67 i am pretty sure i am wrong it's going on decimals.

  20. Nnesha
    • one year ago
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    well i don't understand the 3rd line

  21. calculusxy
    • one year ago
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    if i did 17 - 42.5 = -25.5

  22. Nnesha
    • one year ago
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    yep that's right you need to move 42.5 to the right side then you will get Perfect one

  23. calculusxy
    • one year ago
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    what do you mean by moving 42.5?

  24. Nnesha
    • one year ago
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    i meant you have to subtract 42.5 both sides :=)

  25. Jacob902
    • one year ago
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    correct

  26. calculusxy
    • one year ago
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    so what i did was correct right?

  27. Nnesha
    • one year ago
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    \(\color{blue}{\text{Originally Posted by}}\) @calculusxy 42.5 - 17.5y - 8y = 17 42.5 - 25.5y = 17 -25.5 - 25.5y = 17 -25.5y = 42.5 y = 1.67 i am pretty sure i am wrong it's going on decimals. \(\color{blue}{\text{End of Quote}}\) well here 3rd line you need to subtract 42.5 both sides i don't why there is -25.5 -25.5y

  28. calculusxy
    • one year ago
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    oh yeah

  29. calculusxy
    • one year ago
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    my mistake :\

  30. Nnesha
    • one year ago
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    :=) doing gREAT

  31. calculusxy
    • one year ago
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    y = 1 right?

  32. Nnesha
    • one year ago
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    yep right!

  33. calculusxy
    • one year ago
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    and then we would do: -5x - 8(1) = 17 -5x - 8 = 17 -5x = 25 x = -5

  34. Nnesha
    • one year ago
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    gO_OD to go!

  35. calculusxy
    • one year ago
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    thanks :) I have another question. it's small and related to basic physics. can u help?

  36. Nnesha
    • one year ago
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    PHYSICS hmmmm not sure

  37. calculusxy
    • one year ago
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    can u just see it? if u can't do it then u don't have to.

  38. Nnesha
    • one year ago
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    ye sure!

  39. calculusxy
    • one year ago
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    okay. here it is...

  40. calculusxy
    • one year ago
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    If i'm driving in a car at 30kph and a friend is driving in a car with the same mass at 60kph, my friend's car's kinetic energy is bigger than mine by a factor of what? (that is, divide my friend's over mine.)

  41. Nnesha
    • one year ago
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    i'm not sure havn't done physics n a while sorry

  42. calculusxy
    • one year ago
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    okay thank you though :)

  43. Nnesha
    • one year ago
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    np good job!

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