SOLUTION: Hey there, I have recently been set a simultaneous equations hwk that up till now I have found rather easy! My problem occurs at a new type of question I have not been taught about

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Question 1015473: Hey there, I have recently been set a simultaneous equations hwk that up till now I have found rather easy! My problem occurs at a new type of question I have not been taught about. I will provide 2 questions for reference: 2x-y%2B1=0 and 3x%2B2y%2B4=0 is the first pair. The 2nd is 3x-y%2B5=0 and 5x%2By-13=0 is the other pair. I believe that I need to +/-the single integer with no algebraic term, to make it not equal 0, and the rearrange and substitute in. However, when I do this, say with the 2nd, I get x=-9, which I know isn't right, as a friend showed me the answer. But I want to understand how I get there! As the answer is x=1. Thanks for reading and helping me out!
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
2x - y + 1 = 0
3x + 2y + 4 = 0
-------
4x - 2y + 2 = 0 1st eqn times 2
3x + 2y + 4 = 0
--------------------- Add
7x + 6 = 0
x = -6/7
y = 2x + 1 (1st eqn)
y = -5/7
=====================
3x - y + 5 = 0
5x + y - 13 =0
----------------------- Add
8x - 8 = 0
x = 1
=====================================
---
y = 8
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