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anonymous

  • one year ago

3x+(5/2)y=21 x+2y=14 can someone help me solve this plzzz.

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  1. kropot72
    • one year ago
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    You can find x in terms of y by rearranging the second equation as follows: x + 2y = 14 Therefore: x = 14 - 2y Do you understand this first step?

  2. anonymous
    • one year ago
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    your subtracting 2y from both sides?

  3. kropot72
    • one year ago
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    Yes, you are correct. Now we can plug this expression for x into the first equation 3x + (5/2)y = 21 giving 3(14 - 2y) + (5/2)y = 21 which expands to 42 - 6y + (5/2)y = 21 Can you now solve this last equation to find the value of y?

  4. anonymous
    • one year ago
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    first I think is 21 - 42 which is -2. 6y + (5/2)y= -21 after that i'm kinda confused

  5. UsukiDoll
    • one year ago
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    \[3x+ \frac{5}{2}y=21\] \[x+2y=14\] I think dealing with the fraction is a chore... maybe we can multiply 2 throughout the first equation so we can have whole numbers to work with

  6. anonymous
    • one year ago
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    yea im not good with fractions

  7. UsukiDoll
    • one year ago
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    \[3(2)x+ \frac{5(2)}{2}y=21(2)\] \[6x+ 5y=42\] \[x+2y=14\]

  8. UsukiDoll
    • one year ago
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    we could use subsitution by using the second equation x=14-2y and then plug it into the first equation

  9. UsukiDoll
    • one year ago
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    \[6(14-2y)+ 5y=42\]

  10. kropot72
    • one year ago
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    The equation simplifies to - (7/2)y = -21 Now you can multiply both sides by -2 to give 7y = 42

  11. anonymous
    • one year ago
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    6

  12. kropot72
    • one year ago
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    yes y = 6 is correct.

  13. UsukiDoll
    • one year ago
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    \[84-12y+5y=42 \rightarrow 84-7y=42\] \[-7y=42-84 \rightarrow -7y=-42 \rightarrow y=6\]

  14. UsukiDoll
    • one year ago
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    yup y = 6

  15. anonymous
    • one year ago
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    yay :D

  16. UsukiDoll
    • one year ago
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    so now we can plug y = 6 back into one of the equations.. let's try the second equation x+2y = 14

  17. UsukiDoll
    • one year ago
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    x+2(6)=14 x+12=14

  18. kropot72
    • one year ago
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    Which shows there is more than one way to skin a cat, if you forgive the analogy :)

  19. UsukiDoll
    • one year ago
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    ewwww I own cats in real life

  20. anonymous
    • one year ago
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    x=2 n I had a cat once

  21. kropot72
    • one year ago
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    My bad form :(

  22. UsukiDoll
    • one year ago
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    yes so x = 2 and y = 6 we can plug it back into the original equations to see if we have the right answer.. I know we do because 2+2(6)=14 2+12=14 14=14

  23. anonymous
    • one year ago
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    thank u

  24. UsukiDoll
    • one year ago
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    3(2) +5/2(6/1) = 21 6+(30/2)=21 6+15=21 21=21

  25. anonymous
    • one year ago
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    |dw:1437803748984:dw|

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