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anonymous

  • one year ago

HELP! WILL MEDAL AND FAN!! Solve the following system of equations: -2x + y = 1 -4x + y = -1

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  1. ybarrap
    • one year ago
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    Add the 1st equation to the negative of the 2nd equation. What do you get?

  2. anonymous
    • one year ago
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    Y= -2x + 1 and Y= -4x - 1

  3. anonymous
    • one year ago
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    Y= -2x + 1 and Y= -4x - 1

  4. ybarrap
    • one year ago
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    Like this -2x + y = 1 plus -(-4x + y = -1) equals -2x -(-4x) + y - y = 1 -(-1) Do you see what happened here?

  5. anonymous
    • one year ago
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    yeah

  6. ybarrap
    • one year ago
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    So what do you think we should do with that last equation?

  7. anonymous
    • one year ago
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    solve it or simplify it

  8. ybarrap
    • one year ago
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    Ok, try it out - I'll watch and help

  9. anonymous
    • one year ago
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    are you tring to put it into y= form?

  10. ybarrap
    • one year ago
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    How can we simplify this - -2x -(-4x) + y - y = 1 -(-1) ?

  11. anonymous
    • one year ago
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    -2x+y=1

  12. ybarrap
    • one year ago
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    See the y - y will cancel to become zero $$ -2x -(-4x) + 0 = 1 -(-1)\\ $$ What's else can we do?

  13. anonymous
    • one year ago
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    subtract the values and get -6x

  14. ybarrap
    • one year ago
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    Close The -(-4x) becomes just 4x: $$ -2x +4x + 0 = 1 -(-1)\\ $$ Now what?

  15. ybarrap
    • one year ago
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    What is -2x + 4x ?

  16. anonymous
    • one year ago
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    2x

  17. ybarrap
    • one year ago
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    yes! So now we have $$ 2x+0=1-(-1) $$ What's can we do next?

  18. anonymous
    • one year ago
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    2x+0=-2

  19. ybarrap
    • one year ago
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    -(-1) = 1 Remember, negative of a negative number makes it positive Try again

  20. anonymous
    • one year ago
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    2x+0=1

  21. ybarrap
    • one year ago
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    $$ 2x+0=1-(-1)=1+1 $$ Do you see that? What's next?

  22. anonymous
    • one year ago
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    2x+0=2

  23. ybarrap
    • one year ago
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    yes! Ok, what do we do now?

  24. anonymous
    • one year ago
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    subtract 0 from both sides and get 2x=2

  25. ybarrap
    • one year ago
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    What next?

  26. anonymous
    • one year ago
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    the answer choices are A. (3,1) B (-1,3) C (-1,-3) D (1,3)

  27. ybarrap
    • one year ago
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    We need x by itself, what do we need to divide out on both sides to make 2x equal to just x ?

  28. anonymous
    • one year ago
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    2 divided by both sides

  29. ybarrap
    • one year ago
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    Yes! We need to divide 2 to both sides: $$ \cfrac{2x}{2}=\cfrac{2}{2}=? $$ What does this give us for x?

  30. anonymous
    • one year ago
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    x=0

  31. anonymous
    • one year ago
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    x=1

  32. ybarrap
    • one year ago
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    Yes! Now you know one variable. Now let's use one of your original equations to get y Let's use this one $$ -2x + y = 1 $$ Plug in x=1 and see what you get for y.

  33. ybarrap
    • one year ago
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    $$ -2\times 1 + y = 1 $$ So now what is y?

  34. anonymous
    • one year ago
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    -2y=1

  35. ybarrap
    • one year ago
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    $$ -2\times 1 + y = -2+y=1 $$ See that?

  36. anonymous
    • one year ago
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    yeah

  37. ybarrap
    • one year ago
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    How do you move the -2 to the other side of the equal sign?

  38. anonymous
    • one year ago
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    im so confused this isnt leading to any of the answer choices

  39. anonymous
    • one year ago
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    and i have so many more questions in so little time

  40. ybarrap
    • one year ago
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    Add 2 to both sides of this equation $$ -2+y+2=1+2 $$ What does this give us?

  41. anonymous
    • one year ago
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    -2 + 2y = 3

  42. ybarrap
    • one year ago
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    Almost there $$ -2+2+y=3 $$

  43. ybarrap
    • one year ago
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    What's -2 + 2?

  44. anonymous
    • one year ago
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    0

  45. anonymous
    • one year ago
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    y=3

  46. ybarrap
    • one year ago
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    Yes! So now you know everything. x=1 y=3 (1,3)

  47. anonymous
    • one year ago
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    oh thats make so much sense thanks so much

  48. ybarrap
    • one year ago
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    When you do one on your own, all the others will be like adding 1+1=2

  49. ybarrap
    • one year ago
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    do another on your own right here

  50. ybarrap
    • one year ago
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    Have some courage my friend, everything takes time -- don't worry about the little things.

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