## Algebra and Trigonometry 10th Edition

$y$ varies directly as $x$
- First: as $x$ increases, $y$ increases too. - Second: when $x$ goes from 1 to 2 (2 is the double of 1), $y$ goes from 1.5 to 3 (3 is the double of 1.5). When $x$ goes from 1 to 4 (4 is four times 1), $y$ goes from 1.5 to 6 (6 is four times 1.5) We conclude that $y$ varies directly as $x$.