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anonymous

  • 5 years ago

Can you show me how to solve this equation using substitution 5y+4x=8 y=5x+10

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  1. amistre64
    • 5 years ago
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    yes. since it is stated that y = 5x +10; we can just substitute that value for "y" in the other equation and slove for "x"

  2. amistre64
    • 5 years ago
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    5(5x + 10) + 4x = 8 25x + 50 + 4x = 8 29x + 50 = 8 29x = 8 - 50 29x = -42 x = -42/29

  3. amistre64
    • 5 years ago
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    reduce if you can...

  4. anonymous
    • 5 years ago
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    could you show me what I did wrong ill show you how I solved it

  5. amistre64
    • 5 years ago
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    go right ahead :)

  6. anonymous
    • 5 years ago
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    5y+4x=8 y=5x+10 5(5x+10)+4x=8 25x+50+4x=8 21x+50=8 21x=-42 x=-2 y=5(-20)+10 y=-10+10 y=0

  7. anonymous
    • 5 years ago
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    That is what I did

  8. anonymous
    • 5 years ago
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    And I was pretty sure that was the answer.

  9. amistre64
    • 5 years ago
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    25x + 4x does NOT equal 21x

  10. anonymous
    • 5 years ago
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    Oh sorry I made a typing misatke to y=5(-2)+10 should be the one line

  11. anonymous
    • 5 years ago
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    Ithought you subtracted

  12. amistre64
    • 5 years ago
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    nope; when it says 25 + 4, it actually means to add. That little (+) sign means add....

  13. anonymous
    • 5 years ago
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    I know but I was taught that you did the opposite to get rid of it

  14. amistre64
    • 5 years ago
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    why would you want to get rid of it? it is a vital part of the equation. Now, if it was on the OTHER side of the (=) sign, you would subtract it from BOTH sides to move it. But, if it is on the SAME side, it is simply addition.... Does that make sense?

  15. anonymous
    • 5 years ago
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    Look at your original question that you asked. Are you sure it doesn't say -4x in the problem you were given? 5y - 4x = 8?

  16. anonymous
    • 5 years ago
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    Hold on let me check quick

  17. amistre64
    • 5 years ago
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    If you want to move it to the othe side of the (=) sign we do this: 25 + 4 = 29 25 + 4 (-4) = 29 (-4) 25 = 29 - 4 But when it is on the same side, just add it together: 25 + 4 = 29 29 = 29

  18. anonymous
    • 5 years ago
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    5y + 4x = 8 y + 5x = 10 it says ''solving a system of equations by substitution''

  19. amistre64
    • 5 years ago
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    That is a different set of equations that what you give to begin with; please verify which one is correct please...

  20. anonymous
    • 5 years ago
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    Im sorry

  21. anonymous
    • 5 years ago
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    The last one is the correct one

  22. amistre64
    • 5 years ago
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    ok :) What does "y" equal then?: y = 10 - 5x substitute that "value" into the top equation to get: 5(10 - 5x) + 4x = 8 50 - 25x + 4x = 8 -25x + 4x = 8 -50 -21x = -42 x = -42/-21 = 2 Use this solid value of x=2 in the bottom equation to solve for "y" y + 5(2) = 10 y + 10 = 10 y = 10 - 10 y = 0 x = 2

  23. anonymous
    • 5 years ago
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    OK thanks im gonna look over this for a minute

  24. anonymous
    • 5 years ago
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    Im sorry im kinda confussed I was taught in a different way and im trying to figure this all out

  25. anonymous
    • 5 years ago
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    I got y=5x+10

  26. amistre64
    • 5 years ago
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    you gave, for the bottom equation: y + 5x = 10 ; to get "y" all by its little lonesome, we need to subtract (5x) from both sides to keep the same values... y +5x -5x = 10 - 5x y + 0 = 10 - 5x y = 10 - 5x Do you see it?

  27. anonymous
    • 5 years ago
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    Not really im sorry

  28. amistre64
    • 5 years ago
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    tell me where I am losing you then, let me know what is confusing you here. And then I can show you the right steps...

  29. amistre64
    • 5 years ago
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    Can you tell me what the (=) sign means?

  30. anonymous
    • 5 years ago
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    See for Y im somehow got -5x+10

  31. amistre64
    • 5 years ago
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    -5x + 10 is correct, and it is the same thing as 10-5x am i right or wrong?

  32. anonymous
    • 5 years ago
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    Oh so then I did have it right?

  33. amistre64
    • 5 years ago
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    you wrote, and I quote " I got y=5x+10" earlier. If what you meant was "I got y= -5x+10" then yes, you are right...

  34. anonymous
    • 5 years ago
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    Yeah thats what I meant im sorry I cant type today at all

  35. amistre64
    • 5 years ago
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    :) paper and pencil is always easier when doing math

  36. anonymous
    • 5 years ago
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    Yeah it is but thanks for showing me that now im gonna rework the problem and see if i get it right

  37. anonymous
    • 5 years ago
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    so should the set up be 5(-5x+10)+4x=8

  38. amistre64
    • 5 years ago
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    Yes

  39. anonymous
    • 5 years ago
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    Ok I think im getting this down now

  40. amistre64
    • 5 years ago
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    you are doing great :)

  41. anonymous
    • 5 years ago
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    Thanks I have really been having a tough time this year

  42. anonymous
    • 5 years ago
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    Does y = 2

  43. anonymous
    • 5 years ago
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    and x=0

  44. amistre64
    • 5 years ago
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    yes; y=0 and x=2. To double check; plug those values into the original equations to see if they are true.

  45. anonymous
    • 5 years ago
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    Ok thanks a lot :)

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