Difference between revisions of "2024 SSMO Speed Round Problems/Problem 7"

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==Solution==
 
==Solution==
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The answer is <cmath>\left(\left(\sum_{i=0}^{10}(-1)^ii^2\right)\left(\sum_{i=0}^{10}(-1)^ii^2\right)\right) = \left(\sum_{i=0}^{10}i\right) = \boxed{3025}.</cmath>
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~SMO_Team

Latest revision as of 14:27, 10 September 2025

Problem

Let $S$ denote the set of all ellipses centered at the origin and with axes $AB$ and $CD$ where $A=(-x,0),B=(x,0),C=(0,-y),$ and $D=(0,y),$ for $2 \mid x+y$ and $0\le x,y \le 10.$ Let $T$ denote the set of similar ellipses centered at the origin and passing through $(x,y)$ for $2 \nmid x+y$ and $0\le x,y,\le 10.$ If the positive difference between the sum of the areas of all ellipses in $T$ and the sum of the areas of all the ellipses in $S$ is $m\pi,$ find $m.$

Solution

The answer is \[\left(\left(\sum_{i=0}^{10}(-1)^ii^2\right)\left(\sum_{i=0}^{10}(-1)^ii^2\right)\right) = \left(\sum_{i=0}^{10}i\right) = \boxed{3025}.\]

~SMO_Team