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anonymous

  • one year ago

Please Help! Immediately! Use Cramer's Rule to solve this system of equations. Write your answer as an ordered pair, like this (-4, 13) {−2x–12=4y 2y+3x=2

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  1. zzr0ck3r
    • one year ago
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    \[ \left[ \begin{array}{ccc} -2 & -4 \\ 3&2 \end{array} \right]\mathbf{x}= \left[ \begin{array}{ccc} 12 \\ 2 \end{array} \right]\] Where \(\textbf{x}=(x_1,x_2)\) You see how I got this?

  2. anonymous
    • one year ago
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    No. I don't get this at all.

  3. anonymous
    • one year ago
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    Im behind in school and i couldn't figure out that problem i tried working it out but im running out of time. I appreciate you helping. Is (12,2) the answer?

  4. anonymous
    • one year ago
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    Could i get help with this one as well. Use Cramer's Rule to find the solution to this system of equations. Enter your answer as an ordered pair, like this: (-2, 14) {5x+8y=7 3x+10y=−1

  5. UnkleRhaukus
    • one year ago
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    \[-2x–12=4y\\ 2y+3x=2 \\[2ex] -2x-4y=12\\ 3x+2y=2\\[2ex] \begin{bmatrix} -2&-4\\3&2 \end{bmatrix} \begin{bmatrix} x\\y \end{bmatrix} = \begin{bmatrix} 12\\2 \end{bmatrix}\]

  6. anonymous
    • one year ago
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    My answer would be (12,2)?

  7. UnkleRhaukus
    • one year ago
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    no, answer is x, and y

  8. anonymous
    • one year ago
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    How? Im so confused. It says to put my answer in as a ordered pair.

  9. UnkleRhaukus
    • one year ago
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    we have to use Cramer's rule to find (x,y)

  10. UnkleRhaukus
    • one year ago
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    Do you know what Cramer's rule is?

  11. anonymous
    • one year ago
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    No thats what i am confused on

  12. UnkleRhaukus
    • one year ago
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    Cramer's rule says we can find (x, y), with determinants. Do you know how to take the determinant of a matrix?

  13. anonymous
    • one year ago
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    yes

  14. UnkleRhaukus
    • one year ago
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    What is the value of this determinant? \[D = \begin{vmatrix} -2&-4\\3&2\end{vmatrix}\]

  15. anonymous
    • one year ago
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    8

  16. UnkleRhaukus
    • one year ago
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    good, that is D, the determinant of the coefficient matrix

  17. UnkleRhaukus
    • one year ago
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    Switching the first column and the solution column, we get \[D_x = \begin{vmatrix} 12&-4\\2&2\end{vmatrix}\] what is the value of this determinant

  18. anonymous
    • one year ago
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    32

  19. UnkleRhaukus
    • one year ago
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    And this one?\[D_y = \begin{vmatrix} -2&12\\3&2\end{vmatrix}\]

  20. anonymous
    • one year ago
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    -32

  21. UnkleRhaukus
    • one year ago
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    try that one again

  22. anonymous
    • one year ago
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    -40

  23. UnkleRhaukus
    • one year ago
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    ok, so we have found the values of the three determinants D = 8, D_x = 32, D_y = -40.

  24. anonymous
    • one year ago
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    so is my answer (32,-40)

  25. UnkleRhaukus
    • one year ago
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    Cramer's rule says that x = D_x / D y = D_y / D

  26. anonymous
    • one year ago
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    (4,-5)

  27. UnkleRhaukus
    • one year ago
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    hmm, sounds about right, but lets check it

  28. UnkleRhaukus
    • one year ago
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    the first equation we were given is -2x-12 = 4y if (4,-5) is the solution, then -2(4)-12 = 4(-5) is a true statement, is this right?

  29. UnkleRhaukus
    • one year ago
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    The second equation was 2y+3x = 2 if (4,-5) is the solution, then 2(-5)+3(4) = 2 is also true. is this also right?

  30. anonymous
    • one year ago
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    Yes they are both right

  31. UnkleRhaukus
    • one year ago
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    Woo hoo! Then we have done it!

  32. anonymous
    • one year ago
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    Thank you very much that helped so much.

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