The firework is an illustration of the equation of a parabola.
The x-intercepts are 0 and 78, the y-intercept is 0, and the vertex is (39,760.5)
The casings hit the ground after 78 seconds.
This means that, a point on the graph is:
[tex]\mathbf{(x,y) = (78,0)}[/tex]
The firework exploded at a maximum of 760.5.
This means that, the vertex is:
[tex]\mathbf{(h,k) = (39,760.5)}[/tex]
The equation of a parabola is:
[tex]\mathbf{y = a(x - h)^2 + k}[/tex]
So, we have:
[tex]\mathbf{0 = a(78 - 39)^2 + 760.5}[/tex]
[tex]\mathbf{0 = a(39)^2 + 760.5}[/tex]
Subtract 760.5 from both sides
[tex]\mathbf{a(39)^2 =- 760.5}[/tex]
[tex]\mathbf{1521a =- 760.5}[/tex]
Solve for a
[tex]\mathbf{a =- \frac{760.5}{1521}}[/tex]
[tex]\mathbf{a =- 0.5}[/tex]
Substitute [tex]\mathbf{a =- 0.5}[/tex] and [tex]\mathbf{(h,k) = (39,760.5)}[/tex] in [tex]\mathbf{y = a(x - h)^2 + k}[/tex]
[tex]\mathbf{y = -0.5(x - 39)^2 + 760.5}[/tex]
See attachment for the graph of [tex]\mathbf{y = -0.5(x - 39)^2 + 760.5}[/tex].
From the graph:
- The x and y intercepts are the points where the graph crosses the x and y axes.
- The vertex is the maximum point on the graph
From the equation:
- Set x to 0, to calculate the value of y for the y-intercept
- Set y to 0, to calculate the value of x for the x-intercept.
- The vertex is represented as: (h,k)
Hence, the x-intercepts are 0 and 78, the y-intercept is 0, and the vertex is (39,760.5)
Read more about parabolas at:
https://brainly.com/question/5430838
