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Question 62187: I am confused as to solving this linear equation. Should I add them or solve them seperately and how?
2x+7y=11
5x-3y=7.
Thank you.
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! I am confused as to solving this linear equation. Should I add them or solve them seperately and how?
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This is called a system of equations, two unknowns x & y, two equations that can be added or subtracted to eliminate one of the unknowns.
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The idea is to mult one or both equations by values that will eliminate one of the unknowns when they are added or subtracted;
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Looking at this, if we mult the 1st equation by 3 and the 2nd equation by see what we have:
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2x+7y=11 * 3 =
5x-3y=7. * 7 =
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6x + 21y = 33
35x -21y = 49
---------------- adding will eliminate y:
41x + 0y = 82
41x = 82
x = 82/41
x = 2
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Now we know what x is, substiute 2 for x in the 1st equation, find y:
2x + 7y = 11
2(2) + 7y = 11
4 + 7y = 11
7y = 11 - 4
y = 7/7
y = 1
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You should check the solutions in one of the original equations. we used the 1st one to find y, so the use the 2nd one: 5x - 3y = 7
5(2) - 3(1) = 7
10 - 3 = 7, proves our solution
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Did this unconfuse you? Any questions
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