# Chapter 2 - The Derivative - 2.3 Introduction To Techniques Of Differentiation - Exercises Set 2.3 - Page 140: 9

$=-\frac{3}{x^{4}}-\frac{7}{x^{8}}.$

#### Work Step by Step

Restate $\frac{1}{x^{7}}$ as $x^{-7}$. Now, the power rule for derivatives ($[x^{n}]'=nx^{n-1}$) can be used to get $=-3x^{-3-1}-7x^{-7-1}=-\frac{3}{x^{4}}-\frac{7}{x^{8}}.$

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