## Precalculus: Mathematics for Calculus, 7th Edition

$\frac{x^{2}+x+1}{x^{3}}$
$\frac{1}{x}+\frac{1}{x^{2}}+\frac{1}{x^{3}}$ Find the lowest common denominator (i.e. $x^{3}$) and adjust the fractions accordingly: $=\frac{1\times x^{2}}{x\times x^{2}}+\frac{1\times x}{x^{2}\times x}+\frac{1}{x^{3}}$ $=\frac{x^{2}}{x^{3}}+\frac{x}{x^{3}}+\frac{1}{x^{3}}$ Combine the fractions: $=\frac{x^{2}+x+1}{x^{3}}$