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anonymous

  • 4 years ago

Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this. 10x+5y=52.5 30x-7y=80.5

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  1. anonymous
    • 4 years ago
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    multiply the first by -3, add to the second

  2. anonymous
    • 4 years ago
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    ok so 10x*-3

  3. anonymous
    • 4 years ago
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    ok now is the second part or the whole thing

  4. anonymous
    • 4 years ago
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    ok i messed up yet again so let me start afresh

  5. anonymous
    • 4 years ago
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    ok great

  6. anonymous
    • 4 years ago
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    here we go ready?

  7. anonymous
    • 4 years ago
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    \[10x+5y=52.5\] \[30x-7y=80.5\] multiply top by -3 get \[-30x-15y=-157.5\] \[30x-7y=80.5\]

  8. anonymous
    • 4 years ago
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    add the two equations together. the x's add up to zero and you get one equation in y, namely \[-22y=-77\] solve for y and get \[y=\frac{77}{22}=\frac{7}{2}=3.5\]

  9. anonymous
    • 4 years ago
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    now that we know y, replace y by 3.5 in either equation and solve for x

  10. anonymous
    • 4 years ago
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    \[10x+5y=52.5\] \[10x+5\times 3.5=52.5\] \[10x+17.5=52.5\] \[10x=35\] \[x=3.5\]

  11. anonymous
    • 4 years ago
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    so both x and y are 3.5 it doesn't usually work out that way

  12. anonymous
    • 4 years ago
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    ok got it now

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