Difference between revisions of "1985 OIM Problems/Problem 4"

 
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== Solution ==
 
== Solution ==
{{solution}}
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Because <math>x\ne y</math>, by ratio equalities, <math>\frac{yz-x^2}{1-x}=\frac{xz-y^2}{1-y}=\frac{yz-x^2-xz+y^2}{-x+y}=\frac{z(x-y)+(x+y)(x-y)}{x-y}=x+y+z</math>.
  
 
== See also ==
 
== See also ==
 
https://www.oma.org.ar/enunciados/ibe1.htm
 
https://www.oma.org.ar/enunciados/ibe1.htm

Latest revision as of 23:50, 8 April 2024

Problem

If $x \ne 1$, $y \ne 1$, $x \ne y$, and: \[\frac{yz-x^2}{1-x}=\frac{xz-y^2}{1-y}\] Prove that both fractions are equal to $x+y+z$.

~translated into English by Tomas Diaz. ~orders@tomasdiaz.com

Solution

Because $x\ne y$, by ratio equalities, $\frac{yz-x^2}{1-x}=\frac{xz-y^2}{1-y}=\frac{yz-x^2-xz+y^2}{-x+y}=\frac{z(x-y)+(x+y)(x-y)}{x-y}=x+y+z$.

See also

https://www.oma.org.ar/enunciados/ibe1.htm