Difference between revisions of "2023 SSMO Relay Round 2 Problems/Problem 1"

(Created page with "==Problem== Consider the cubic polynomial <math>P(x)=ax^3+bx^2+cx+d</math>, where <math>a,b,c,d</math> are single-digit integers, which has roots of approximately <cmath>x \ap...")
 
 
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==Solution==
 
==Solution==
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Note that the sum of the three roots is approximately <math>0.71\approx\frac{5}{7}</math>. So, we have <math>a=7</math>. Therefore <cmath>|f(3)| \approx 7(3-(-0.95))(3-0.2)(3-1.46)\approx\boxed{119}.</cmath>
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~pinkpig

Latest revision as of 15:30, 15 September 2025

Problem

Consider the cubic polynomial $P(x)=ax^3+bx^2+cx+d$, where $a,b,c,d$ are single-digit integers, which has roots of approximately \[x \approx -0.9518399, 0.2055095, 1.460616.\] Compute $|f(3)|$.

Solution

Note that the sum of the three roots is approximately $0.71\approx\frac{5}{7}$. So, we have $a=7$. Therefore \[|f(3)| \approx 7(3-(-0.95))(3-0.2)(3-1.46)\approx\boxed{119}.\]

~pinkpig