# Chapter 2 - Real Numbers - 2.4 - Exponents - Problem Set 2.4 - Page 75: 60

$-\dfrac{n^2}{9}$

#### Work Step by Step

Because the least common denominator is $18$, we create a common denominator of $18$ and obtain: \begin{array}{l}\require{cancel} \dfrac{9(-1n^2)+3(5n^2)-2(4n^2)}{18} \\\\= \dfrac{-9n^2+15n^2-8n^2}{18} \\\\= \dfrac{-2n^2}{18} \\\\= \dfrac{-\cancel{2}n^2}{\cancel{2}\cdot9} \\\\= -\dfrac{n^2}{9} .\end{array}

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