Difference between revisions of "2007 SMT Algebra Round Problem 1"

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==Solution==
 
==Solution==
After factoring, we get <math>f\left(x^{\frac19}\right)=(x-1)(x+4)</math>, so to make <math>(x-1)(x+4)=0</math>, <math>x=4</math> or <math>-1</math>, so, we have <math>4^{\frac19}</math> or <math>(-1)^{\frac19}</math>, and because <math>4^{\frac19}</math> can't be simplified and <math>(-1)^{\frac19}=-1</math>, our answer is <math>x=\boxed{\mathrm{4^{\frac19} \text{or} -1}}</math>.
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After factoring, we get <math>f\left(x^{\frac19}\right)=(x-1)(x+4)</math>, so to make <math>(x-1)(x+4)=0</math>, <math>x=4</math> or <math>-1</math>, so, we have <math>4^{\frac19}</math> or <math>(-1)^{\frac19}</math>, and because <math>4^{\frac19}</math> can't be simplified and <math>(-1)^{\frac19}=-1</math>, our answer is roots <math>=\boxed{\mathrm{4^{\frac19} \text{ or } -1}}</math>.
  
 
~Yuhao2012
 
~Yuhao2012

Latest revision as of 08:37, 29 October 2025

Problem

Find all real roots of $f$ if $f\left(x^{\frac19}\right)=x^2-3x-4$.

Solution

After factoring, we get $f\left(x^{\frac19}\right)=(x-1)(x+4)$, so to make $(x-1)(x+4)=0$, $x=4$ or $-1$, so, we have $4^{\frac19}$ or $(-1)^{\frac19}$, and because $4^{\frac19}$ can't be simplified and $(-1)^{\frac19}=-1$, our answer is roots $=\boxed{\mathrm{4^{\frac19} \text{ or } -1}}$.

~Yuhao2012