Question 329243
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Step 1 is to subtract an *[tex \Large r].  This is algebra, not algerbra.


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ +\ 6y\ =\ 17]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ -\ 10y\ =\ 9]


Multiply the 2nd equation by -1:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ +\ 6y\ =\ 17]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -2x\ +\ 10y\ =\ -9]


Add the like terms in the two equations:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 0x\ +\ 16y\ =\ 8]


Hence,


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ +\ 6y\ =\ 17]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ y\ =\ \frac{1}{2}]


Substitute this value back into either of the original equations:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ +\ 6\left(\frac{1}{2}\right)\ =\ 17]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x\ \ =\ 14]


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


Therefore the solution set is


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \{(7,\frac{1}{2})\}]



John
*[tex \LARGE e^{i\pi} + 1 = 0]
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