Question

How do you get common denominators? I forgot :/

Answer 1

Multiply on some form of 1, for instance, generically:\[\dfrac{a}{b}+\dfrac{c}{d} = \dfrac{a}{b}\cdot \dfrac{d}{d} + \dfrac{c}{d}\cdot \dfrac{b}{b} = \dfrac{ad}{bd}+\dfrac{bc}{bd} = \dfrac{ad+bc}{bd}\]Assuming b and d are not zero. For more solutions to textbook problems, be sure to check out http://www.slader.com/s/eWFrZXlnbGVl. I submit a lot of content there as well.