SOLUTION: The quadratic function that models the fireworks’ height s(x) in feet x seconds after they are launched is given by the equation s(x) = -16x^2+200x + 4. When should the fireworks

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: The quadratic function that models the fireworks’ height s(x) in feet x seconds after they are launched is given by the equation s(x) = -16x^2+200x + 4. When should the fireworks       Log On


   



Question 87764This question is from textbook Intermediate Algebra
: The quadratic function that models the fireworks’ height s(x) in feet x seconds after they are launched is given by the equation s(x) = -16x^2+200x + 4. When should the fireworks explode so that they go off at the greatest height? What is that height? [Hint: Find the vertex of the quadratic function s(x).] This question is from textbook Intermediate Algebra

Found 2 solutions by stanbon, rapaljer:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The quadratic function that models the fireworks’ height s(x) in feet x seconds after they are launched is given by the equation s(x) = -16x^2+200x + 4. When should the fireworks explode so that they go off at the greatest height? What is that height? [Hint: Find the vertex of the quadratic function s(x).]
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Vertex occurs at x=-b/2a = -200/-32 = 6.25 seconds
Height at that time = s(6.25) = -16^(6.25)^2+200(6.25)+4 = 668.07 ft
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Cheers,
Stan H.

Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
The vertex of the parabola y+=+ax%5E2+%2Bbx+%2Bc occurs at x=-b%2F%282a%29+ .
Therefore, for your function s%28x%29+=+-16x%5E2%2B200x+%2B+4, the vertex occurs at x=+-200%2F%282%28-16%29+%29=+-200%2F-32=25%2F5+=+6.25+ seconds.

The maximum height is at s%286.25%29+=+629+ feet. By the way, I used a graphing calculator, with window: x= [-2,14], y = [-100, 700]. It looks like this:
graph%28+300%2C+600%2C+-2%2C14%2C-100%2C700%2C+-16x%5E2%2B200x+%2B+4%29+

R^2 Retired from SCC