Question 49878: Solve the system by addition
2x-4y=7
4x+2y=9
Answer by BGluvsmath(64)   (Show Source):
You can put this solution on YOUR website! 2x-4y=7
4x+2y=9
multiply the 2nd equation by 2: 8x+4y=18
This gives you 2x-4y=7
8x+4y=18
the y terms cancel out: 10x=25
divide both sides by 10: x=2.5
plug the x-value back into either original equation to solve for y. For simplicity, I chose the 2nd one.
4x+2y=9
4(2.5)+2y=9
10+2y=9
2y=-1
y=-1/2 (or -0.5)
Check: 2(2.5)-4(-0.5)=7
5+2=7
So, the solution is (2.5, -0.5)
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