Find the vertex of 0.4y^2 – 36y + 1000

[Bladesofhalo]

Find the vertex of 0.4y^2 – 36y + 1000

need help fiding the vertex of the following equation

0.4y^2 – 36y + 1000

 

[stapel]

need help [finding] the vertex of the following [expression]

0.4y^2 – 36y + 1000

You cannot have a vertex without a two-variable equation. You have posted a one-variable expression. Please reply with the missing information.

When you reply, please list the method you are supposed to be using (a formula? completing the square? something else?) for finding the vertex, and show all of the steps you have tried so far.

Thank you.

Eliz.

 

[Bladesofhalo]

Sorry

Sorry, heres what Im trying to do.

I have the following equation

a(y) = 0.4y^2 -36y +1000

a = accidents per 100 million kilometers
y = age

Now the question asks, "What age driver appears to be the safest?"

I was told I had to find the vertex to get my answer.

So far, I have the discriminant, which is -304, but from there I do not know how to proceed.

 

[stapel]

Why are you finding the discriminant, when you were asked for the minimum (that is, the vertex), not the zeroes (that is, the intercepts)...?

What process or formula were you given for finding the vertex of a parabola?

Eliz.

 

[Bladesofhalo]

Dont you have to use the quadratic formula to find the vertex?

I think that we had to use the (-b/2a) then substitute it into the equation.

 

[stapel]

Dont you have to use the quadratic formula to find the vertex?

No; you use the Quadratic Formula to find zeroes. You complete the square or use the vertex formula to find vertices.

I think that we had to use the (-b/2a) then substitute it into the equation.

This is the vertex formula for "h", not the Quadratic Formula. Try using this to find the vertex.

Eliz.

 

[tkhunny]

I think that we had to use the (-b/2a) then substitute it into the equation.

-b/2a is right. Skip the quadratic formula, though these 'a' and 'b' are the same guys.

If you are ready for some adventure, find the arithmetic mean of the two zeros given by the quadratic formula. Ponder its meaning...