SOLUTION: what is the solution of the system 7r-9s=17 9r+7s=59 plz and thank you

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Question 376661: what is the solution of the system 7r-9s=17 9r+7s=59
plz and thank you
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Start with the given system of equations:
system%287r-9s=17%2C9r%2B7s=59%29


7%287r-9s%29=7%2817%29 Multiply the both sides of the first equation by 7.


49r-63s=119 Distribute and multiply.


9%289r%2B7s%29=9%2859%29 Multiply the both sides of the second equation by 9.


81r%2B63s=531 Distribute and multiply.


So we have the new system of equations:
system%2849r-63s=119%2C81r%2B63s=531%29


Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:


%2849r-63s%29%2B%2881r%2B63s%29=%28119%29%2B%28531%29


%2849r%2B81r%29%2B%28-63s%2B63s%29=119%2B531 Group like terms.


130r%2B0s=650 Combine like terms.


130r=650 Simplify.


r=%28650%29%2F%28130%29 Divide both sides by 130 to isolate r.


r=5 Reduce.


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49r-63s=119 Now go back to the first equation.


49%285%29-63s=119 Plug in r=5.


245-63s=119 Multiply.


-63s=119-245 Subtract 245 from both sides.


-63s=-126 Combine like terms on the right side.


s=%28-126%29%2F%28-63%29 Divide both sides by -63 to isolate s.


s=2 Reduce.


So the solutions are r=5 and s=2.


Which form the ordered pair .


This means that the system is consistent and independent.


If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim