# Write a quadratic function in vertex form for the parabola

So, in the first parabola, going from the point 3, 9 to 4, 16we would rise 7 and run 1. The slope between those two points is 7. So, the second parabola is broader than the first parabola as illustrated in the graph below.  Features of quadratic functions Video transcript I have a function here defined as x squared minus 5x plus 6. And what I want us to think about is what other forms we can write this function in if we, say, wanted to find the 0s of this function. If we wanted to figure out where does this function intersect the x-axis, what form would we put this in?

And then another form for maybe finding out what's the minimum value of this. We see that we have a positive coefficient on the x squared term. This is going to be an upward-opening parabola.

## Finding the vertex of a parabola in standard form (video) | Khan Academy

But what's the minimum point of this? Or even better, what's the vertex of this parabola right over here? So if the function looks something like this, we could use one form of the function to figure out where does it intersect the x-axis.

So where does it intersect the x-axis? And maybe we can manipulate it to get another form to figure out what's the minimum point.

What's this point right over here for this function? I don't even know if the function looks like this. So I encourage you to pause this video and try to manipulate this into those two different forms. So let's work on it. So in order to find the roots, the easiest thing I can think of doing is trying to factor this quadratic expression which is being used to define this function.

So we could think about, well, let's think of two numbers whose product is positive 6 and whose sum is negative 5. So since their product is positive, we know that they have the same sign. And if they have the same sign but we get to a negative value, that means they both must be negative.

Vertex Form. Let's use a vertex that you are familiar with: (0,0). Use the following steps to write the equation of the quadratic function that contains the vertex (0,0) and the point (2,4). Just as a quadratic equation can map a parabola, the parabola's points can help write a corresponding quadratic equation. Parabolas have two equation forms – standard and vertex. In the vertex form, y = a (x - h) 2 + k, the variables h and k are the coordinates of the parabola's vertex. Follow us: Share this page: This section covers: Factoring Methods; Completing the Square (Square Root Method) Completing the Square to get Vertex Form; Obtaining Quadratic Equations from a Graph or Points.

So let's see-- negative 2 times negative 3 is positive 6. Negative 2 plus negative 3 is negative 5.

So we could rewrite f of x. And so let me write it this way. We could write f of x as being equal to x minus 2 times x minus 3. Now, how does this help us find the zeroes?

Well, in what situations is this right-hand expression, is this expression on the right hand going to be equal to 0? Well, it's the product of these two expressions.

If either one of these is equal to 0, 0 times anything is 0. So this whole thing is going to be 0 if x minus 2 is equal to 0 or x minus 3 is equal to 0. Add 2 to both sides of this equation. You get x is equal to 2 or x is equal to 3.

So those are the two zeroes for this function, I guess you could say. And we could already think about it a little bit in terms of graphing it.

So let's try to graph this thing. So this is x equals 1. This is x equals 2. This is x equals 3 right over there. So that's our x-axis.

## Substitute in Coordinates for the Point

That, you could say, is our y is equal to f of x axis. And we're seeing that we intersect both here and here. When x is equal to 2, this f of x is equal to 0.

When x is equal to 3, f of x is equal to 0. And you could substitute either of these values into the original expression. And you'll see it's going to get you to 0 because that is the same thing as that.

Now, what about the vertex?If the quadratic is written in the form y = a(x – h) 2 + k, then the vertex is the point (h, k).This makes sense, if you think about it.

The squared part is always positive (for a right-side-up parabola), unless it's zero. The function f(x) = ax 2 + bx + c is the quadratic function.

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The graph of any quadratic function has the same general shape, which is called a attheheels.com location and size of the parabola, and how it opens, depend on the values of a, b, and attheheels.com shown in Figure 1, if a > 0, the parabola has a minimum point and opens attheheels.com a parabola .

Guess and Check “Guess and Check” is just what it sounds; we have certain rules, but we try combinations to see what will work. NOTE: Always take a quick look to see if the trinomial is a perfect square trinomial, but you try the guess and attheheels.com these cases, the middle term will be twice the product of the respective square roots of the first and last terms, as we saw above.

(We will discuss projectile motion using parametric equations here in the Parametric Equations section.). Note that the independent variable represents time, not distance; sometimes parabolas represent the distance on the \(x\)-axis and the height on the \(y\)-axis, and the shapes are attheheels.com versus distance would be the path or trajectory of the bouquet, as in the following problem.

Vertex Form. Let's use a vertex that you are familiar with: (0,0). Use the following steps to write the equation of the quadratic function that contains the vertex (0,0) and the point (2,4). IXL's dynamic math practice skills offer comprehensive coverage of California high school standards. Find a skill to start practicing! Guess and Check “Guess and Check” is just what it sounds; we have certain rules, but we try combinations to see what will work. NOTE: Always take a quick look to see if the trinomial is a perfect square trinomial, but you try the guess and attheheels.com these cases, the middle term will be twice the product of the respective square roots of the first and last terms, as we saw above. 