A step by step procedure on how to graph a quadratic equation with only 1 solution (discriminant is 0) and no real solutions (complex and discriminant is negative) ? Please provide an example equation and solve through it...
2 Answers
Here you go:
Explanation:
(All work is done with quadratic converted to vertex form. Graphing tends to be easier when converted to vertex form)
There are two ways to solve this problem, and they both work no matter what your discriminant is.
Let's try the equation
graph{(x-6)^2 +5 [-1, 10, -1, 10]} *
First Method: Counting Points
Caution: This method is not generally encouraged by math teachers but is a general rule for quadratics.
1.) Because our answer is in vertex form, we already have one point: the vertex. Go ahead and graph that first. In the case of this function, the vertex is at the point
2.) Now that you have the vertex, start from that point and go up one point and over one point (in both directions) and plot those points.
3.) When you finish with that, move over one point and up three from the previous two you graphed.
5.) Do this as many times as needed, but every time you go to plot your y-value, make sure that you go up to more than you did the previous time (so if you went up one, go up three. If you went up three, go up five. If you went up five, go up seven).
6.) This method is supported by the graph of the function
X | Y
4 | 9
5 | 6
6 | 5
7 | 6
8 | 9
See how the y-values are only one higher than they are at the vertex when the function is evaluated at
Second Method: Calculating Y-Values
This method is supported by math teachers
1.) Again, start by graphing the vertex, which is at point
2.) Start plugging in values for
3.) Graph the y-value you find for whatever value you plugged in for
4.) Example:
Hope this is what you were looking for! Didn't average any roots but it seems to answer your question about not having any!
Explanation:
Let's say we want to graph the function
graph{x^2 -12x +41 [-5.15, 18.78, -0.74, 11.22]}
But how do we get here from the standard form of the equation? First, let's start by finding the vertex.
Now the first step in finding the vertex is finding the axis of symmetry (AOS), which is the verticle line that completely bisects the function. The line's equation follows the pattern
To find the AOS, we simply have to use the equation
So, to find the AOS of this graph we simply plug-in
Well, that's great and all, but now how do we find
Awesome! Now we know that our
Now to continue. So we have our vertex, but how do we figure out the rest of our points? Simple! We plug-in values for
Let's go ahead and do that:
Vuala! Now we can graph these points, and thus, our function has been graphed as well! The graph of this function above will prove my work and I hope this helps!