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What is the system of equations for 3x - 2y =9 and y= 2x - 7

User Naoe
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2 Answers

3 votes
"y" is equivalent to "2x-7" so, this means you are able to substitute it into the first equation, like this:
3x - 2y = 9
3x-2(2x-7)=9
3x-4x+14=9
-1x=-5
x=5
"x=5" is our first answer, now we are going to do the second step which is solve for "y".
y=2x-7
y=2(5)-7
y=10-7
y=3
Now that you've gotten y=3, put both 5 and 3 into this (x,y) which would be (5,3).
Therefore your answer is:
(5,3)

Good luck with your studies, I hope this helps~!
User Markus Winand
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5 votes
Okay so since it gives you a y = id use substitution. So sybarite it in th either equation. You'd have
1: 3x - 2(2x-7) = 9.
2: use order of operations and substitute the 2. 3x - 4x+ 14= 9
3: combine like terms. -x+14= 9
4: solve for X. X= 5
5: plug X back into one of the ORIGINAL equations. So let's just use the y = equation. Y = 2(5) -7
7: solve for y. Y = 3
8: the final solution is x,y which is (5,3)
User FolksLord
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