Chapter 11 - Rational Expressions and Functions - 11-1 Simplifying Rational Expressions - Got It? - Page 664: 1

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Applying power rules: a) $\frac{21a^2}{7a^3}=\frac{3.7.a^2}{7.a^2.a}=\frac{3}{a}$ b) $\frac{18d^2}{4d+8}=\frac{2.9d^2}{2(2d+4)}=\frac{9d^2}{2d+4}$ c) $\frac{2n-3}{6n-9}=\frac{2n-3}{3(2n-3)}=\frac{1}{3}$ d) $\frac{26c^3+91c}{2c^2+7}=\frac{13c(2c^2+7)}{2c^2+7}=13c$