Difference between revisions of "2024 SSMO Relay Round 4 Problems/Problem 3"

(Created page with "==Problem== Let <math>T = TNYWR.</math> Given that: \begin{align*} a+b &= -c,\\ a^3 - abc &= 4,\text{ and }\\ b^3 - abc &= T.\\ \end{align*} Then, <math>abc - c^3 = x.</math>...")
 
 
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==Solution==
 
==Solution==
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Since <math>a+b = -c\implies a+b+c = 0,</math> we have <cmath>a^3+b^3+c^3-3abc = (a+b+c)(a^2+b^2+c^2-ab-ac-bc) = 0.</cmath> So, <math>4+T-x = 0\implies x = 4+T = \boxed{206}.</math>
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~SMO_Team

Latest revision as of 14:47, 10 September 2025

Problem

Let $T = TNYWR.$ Given that: \begin{align*} a+b &= -c,\\ a^3 - abc &= 4,\text{ and }\\ b^3 - abc &= T.\\ \end{align*} Then, $abc - c^3 = x.$ Find the value of $x.$

Solution

Since $a+b = -c\implies a+b+c = 0,$ we have \[a^3+b^3+c^3-3abc = (a+b+c)(a^2+b^2+c^2-ab-ac-bc) = 0.\] So, $4+T-x = 0\implies x = 4+T = \boxed{206}.$

~SMO_Team