Thread: Find expressions for the quadratic functions

Find expressions for the quadratic functions whose graphs are shown:

Originally Posted by question111

Find expressions for the quadratic functions whose graphs are shown:

there are several ways to approach this. here's one

note that the vertex is on the x-axis, that is, we have a double root for the vertex

thus, our quadratic is of the form

we are given that the point (4,2) is on the graph, we can use this to find , by plugging in and into the form above

what is your answer?

Originally Posted by question111

Find expressions for the quadratic functions whose graphs are shown:

Your image is so small that it is very hard to see the co-ordinate of vertex and a point in parabola. Please write these coordinates, then it will be solved.

Originally Posted by Shyam

Your image is so small that it is very hard to see the co-ordinate of vertex and a point in parabola. Please write these coordinates, then it will be solved.

if you click on the image, it takes you to a larger one

So a would be 2, and when I plug that in, I am finally getting a graph like it's shown in the book.

Thank you very much.

Originally Posted by question111

So a would be 2, and when I plug that in, I am finally getting a graph like it's shown in the book.

Thank you very much.

yes, a = 2, that's your quadratic

Originally Posted by lovegreen

i do not understand your question. we found that a = 2. just plug that into the expression given in post #2 to get the quadratic

I see it is y = 2(x squared) -12x + 18

Originally Posted by lovegreen

I see it is y = 2(x squared) -12x + 18

Why not just leave it as ?