Question 806781
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You have the correct process and got to half of the right answer, but you expressed the last step incorrectly.


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  2x\ =\ 8\]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  x\ =\ \frac{8}{2}\ =\ 4]


But that is only half of the problem.  What is the value of *[tex \Large y]?


Now that you have found the value of *[tex \Large x], substitute back into either of your original equations:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  x\ +\ y\ =\ 1]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  4\ +\ y\ =\ 1]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  y\ =\ 1\ -\ 4\ =\ -3]


Finally, check the coordinates of your ordered pair solution set in the other equation:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  x\ -\ y\ =\ 7]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  4\ -\ (-3)\ =^?\ 7]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  4\ +\ 3\ =\ 7\ \ ]Checks.


Now you can report that the solution set of the given system contains a unique ordered pair, and the solution set is  *[tex \Large \left\{\left(4,-3\right)\right\}]


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
<font face="Math1" size="+2">Egw to Beta kai to Sigma</font>
My calculator said it, I believe it, that settles it
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