<p>oh, my bad. I didnt look at the book.
here s website that explains the first one ( #15) . it’s really easy…
[Advanced</a> Graphing - Cool math Algebra Help Lessons - Sideways Parabolas](<a href=“http://www.coolmath.com/algebra/21-advanced-graphing/05-sideways-parabolas-03.htm]Advanced”>http://www.coolmath.com/algebra/21-advanced-graphing/05-sideways-parabolas-03.htm)</p>