# Chapter 10 - Exponents and Radicals - 10.8 The Complex Numbers - 10.8 Exercise Set: 93

$-125i$

#### Work Step by Step

Using $i^2=-1$ and the laws of exponents, the given expression, $(5i)^{3} ,$ is equivalent to \begin{array}{l}\require{cancel} 5^3i^3 \\\\= 125i^3 \\\\= 125i^2\cdot i \\\\= 125(-1)\cdot i \\\\= -125i \end{array}

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