Difference between revisions of "1987 USAMO Problems/Problem 1"

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By expanding you get <math></math>m^3+mn+m^2n^2 +n^3=m^3-3m^2n+3mb^2-n^3<math>.</math>
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By expanding you get <cmath>m^3+mn+m^2n^2 +n^3=m^3-3m^2n+3mb^2-n^3</cmath>
From this the two m^3 cancel and you get:
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From this the two <math>m^3</math> cancel and you get:
 
<cmath>2n^3 +mn+m^2n^2 + 3m^2n - 3mn^2=0</cmath>
 
<cmath>2n^3 +mn+m^2n^2 + 3m^2n - 3mn^2=0</cmath>
 
You can divide by <math>n</math> (nonzero).
 
You can divide by <math>n</math> (nonzero).
 
You get:
 
You get:
 
<cmath>2n^2+m+m^2n+3m^2-3mn=0</cmath>
 
<cmath>2n^2+m+m^2n+3m^2-3mn=0</cmath>
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You can now factor  the equation into:
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<cmath>2n^2+(m^2-3m)n+(3m^2+m)=0</cmath>

Revision as of 11:17, 20 December 2015

By expanding you get \[m^3+mn+m^2n^2 +n^3=m^3-3m^2n+3mb^2-n^3\] From this the two $m^3$ cancel and you get: \[2n^3 +mn+m^2n^2 + 3m^2n - 3mn^2=0\] You can divide by $n$ (nonzero). You get: \[2n^2+m+m^2n+3m^2-3mn=0\] You can now factor the equation into: \[2n^2+(m^2-3m)n+(3m^2+m)=0\]