Chapter 6 Rational Exponents and Radical Functions - Evaluate nth Roots and Use Rational Exponents - 6.1 Exercises - Skill Practice - Page 417: 2

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Consider a negative number $s$. $s^4$ is positive but $s^5$ is negative. Also, consider a number $r$ which is positive. Both $r^4$ and $r^5$ are positive. Thus the sign of $a$ is important as a fourth root will have multiple roots or no roots, and the fifth root will have 1 either way, whether it be positive or negative.