SOLUTION: how can i telln if a graph opens up or down by looking at the equation

Question 213552: how can i telln if a graph opens up or down by looking at the equation
Found 2 solutions by rapaljer, drj:
Answer by rapaljer(4671) (Show Source): You can put this solution on YOUR website!
If you are talking about a parabola like y=x^2, the if the coefficient of x^2 is positive, it opens UP. If the coefficient of x^2 is negative, then the graph opens DOWN.

For example, y =4x^2 -6x +2 opens UP
y=-4x^2 -6x+2 opens DOWN

For additional information on combining parabolas, see my own website. You can do a "Bing" search for my last name "Rapalje". At the top of the search list, look for "Rapalje Homepage". Near the top of my Homepage, look for the link "MATH IN LIVING COLOR." Choose "College Algebra" and look in for Chapter 2 for Section 2.03 Parabolas. I've taught a LOT of methods of graphing parabolas! This is what I consider the easiest way to do it!

R^2

Dr. Robert J. Rapalje, Retired
Seminole Community College
Altamonte Springs Campus
Florida
Answer by drj(1380) (Show Source): You can put this solution on YOUR website!
How can I tell if a graph opens up or down by looking at the equation

For the quadratic equation: if a>0 it will open up. if a<0 it will open down.

Let's look at an example:

for a=2, b=2 and c=1

for a=-2, b=2 and c=1

I hope the above steps were helpful.

For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

Good luck in your studies!

Respectfully,
Dr J
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