Why This Equation Equals -1

  • Thread starter mike_302
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103
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This is not a very difficult question, by any means, and I see that the answer does equal -1, but I do not see the mathematical steps that go on to prove that (y-2)/(2-y)=-1 .. Can someone show me the steps that go through that? Thanks in advance.
 
6
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Dude...

1) (y-2)/(2-y)=-1
2) (y-2)=-1(-y+2)
3) (y-2)=(y-2)

Wait a bit and I'll post the same in TeX.
 
6
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Better way.

[tex]\frac{y-2}{2-y}=\frac{(y-2)(y+2)}{(2-y)(2+y)}=\frac{y^2-4}{4-y^2}=-1[/tex]
 
103
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lol, ok sorry. That was posted slightly incorrectly the first time. Basically, the textbook says "simplify: (y-2)/(2-y) " and the back of the book gives the final answer to be -1, so I can't do the left side right side stuff
 
103
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ahh, yes, I see your second post now . That does seem to be better. Thanks
 
103
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so basically what I do in your second post is I multiply the bottom and top by the conjugate of the denominator?
 
6
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Last edited by a moderator:
6
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Wow, I'm stupid...

[tex]\frac{y-2}{2-y}=\frac{-1(2-y)}{2-y} =-1[/tex]

This is what you get for not doing any maths for almost a year.
 
103
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OH! Jeeeze. I see, lol, Thanks. and, yes. Normally I post in the math homework forums but I think I just clicked on the wrong link and got here. I didn't notice that, sorry.
 

JasonRox

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Hurkyl

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(y-2)/(2-y) = -1 is an equation

(y-2)/(2-y) is not an equation; it's an expression.
 

Tom Mattson

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and the back of the book gives the final answer to be -1, so I can't do the left side right side stuff
It's -1 for all real numbers y not equal to 2. :wink:
 

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