Thread: Textbook algebra graphing help

1. Textbook algebra graphing help

i have a problem where i have to find the maximum height of a dome with a parabolic curve equation of f(x)= -0.0016xsquared + 75.

the 2nd part is finding the minimum height of the dome if the total length is 250 yards.

please help i have no clue on this

2. Originally Posted by Ryan7123
i have a problem where i have to find the maximum height of a dome with a parabolic curve equation of f(x)= -0.0016xsquared + 75.

the 2nd part is finding the minimum height of the dome if the total length is 250 yards.

please help i have no clue on this
Which way does this parabola point? Is it opening up or opening down?

Answer:
Spoiler:
opening down

Next part:
Spoiler:
So if it opens down the highest point will be the vertex of the parabola. How do you find the vertex?

3. i have no clue i havent had time to stay for extra help with my teacher this whole concept i have no idea how to do

4. Originally Posted by Ryan7123
i have no clue i havent had time to stay for extra help with my teacher this whole concept i have no idea how to do
Ok. Well we won't be able to teach you entire chapters in your book. So if you really know nothing about parabolas I suggest you read the section in your book where they are covered.

The standard form for a parabola is $y=ax^2+bx+c$. You can see that your problem is in this form. Since you have a negative number in front of "a", that makes the parabola flip and it goes down. The highest point will be the vertex, which can be found by $x=\frac{-b}{2a}$ in the equation I showed you. That's the x-coordinate.

Does any of this sound familiar or make sense?