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anonymous

  • 5 years ago

The sum of three numbers is 12. The first number is twice the sum of the second and third. The third number is 5 less than the first. Find the number. The key is: first is 8, second is 1, third is 3 This is complicated if you have to show your work and not just guess and check. Set up the equations first.

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  1. anonymous
    • 5 years ago
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    There aren't really equations. You just have to use logic. Use that Logic, process of elimination.. I'm not sure what level of math you are in though

  2. anonymous
    • 5 years ago
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    this is algebra 2

  3. anonymous
    • 5 years ago
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    if you set up equation I know how to solve

  4. anonymous
    • 5 years ago
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    You could maybe use probability. Are you learning about Cnr and Pnr?

  5. anonymous
    • 5 years ago
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    yes I can do

  6. anonymous
    • 5 years ago
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    I can solve you don't have to solve , you just help me set up equation

  7. anonymous
    • 5 years ago
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    umm okay i'm not sure if this is right but

  8. anonymous
    • 5 years ago
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    figure out how many sums of 3 DIFFERENT (whole) numbers add up to 12. so 12*11*10

  9. anonymous
    • 5 years ago
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    so thats your total possibilities and now u can narrow it down

  10. anonymous
    • 5 years ago
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    given the key

  11. anonymous
    • 5 years ago
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    \[\{a+b+c=12,a=-10+2 a+2 b,c=a-5\} \]\[\{\{a\to 8,b\to 1,c\to 3\}\} \]

  12. anonymous
    • 5 years ago
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    thankyou haha

  13. anonymous
    • 5 years ago
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    robtobey how yu get number 10 and 5 ,

  14. anonymous
    • 5 years ago
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    the key for check answer not the given

  15. anonymous
    • 5 years ago
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    I'm working on a response.

  16. anonymous
    • 5 years ago
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    I still don't get ,how you get -10?

  17. anonymous
    • 5 years ago
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    {a + b + c = 12, a = 2 (b + c) , c = a - 5} Replace c in the first two equations with (a-5) {-5 + 2 a + b = 12, a = 2 (-5 + a + b)} Expand the second equation above by multiplying through by 2 {-5 + 2 a + b == 12, a == -10 + 2 a + 2 b} Solve the above two equations for a and b Take the value of a and plug it into c = a - 5 to obtain the value of c I hope I got this correct.

  18. anonymous
    • 5 years ago
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    thanks

  19. anonymous
    • 5 years ago
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    You are welcome.

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