Question 475337
*[tex \LARGE a < b], divide both sides by ab (a positive number).


*[tex \LARGE \frac{a}{ab} < \frac{b}{ab}]


*[tex \LARGE \frac{1}{b} < \frac{1}{a}]


*[tex \LARGE \frac{1}{a} > \frac{1}{b}], done.