contestada

A rock is thrown in the air from the edge of a seaside cliff. Its height in feet is represented by f(x) = –16(x2 – 3x – 18), where x is the number of seconds since the rock was thrown. The height of the rock is 0 feet when it hits the water.How long does it take the rock to hit the water? How many seconds?

Respuesta :

altavistard
Set the given equation equal to zero (0), since that's the height of the rock when it hits the water:

0 = -16(x^2 - 3x - 18)  (Note:  Please write x^2 to denote "square of x.")

Solving this equation for x, we get:

0 = -16(x-6)(x+3), and x=-3 or x=6.  Since x represents time, discard the negative value x=-3.

The rock hits the water after 6 seconds.

The time it takes the rock to hit the water is 6 seconds

Data;

  • f(x) = -16(x^2 - 3x -18)

Time it takes for the rock to hit the ground?

To find the time it takes for the rock to hit the ground, we have to use the and assume that the given equation represents the height at which the rock attained.

[tex]f(x) = -16(x^2 - 3x -18)\\0 = -16x^2 + 48x + 288\\16x^2 - 48x - 288 = 0\\x^2 - 3x - 18 = 0[/tex]

Solving the above quadratic equation,

x = - 3 or x = + 6

The time it takes the rock to hit the water is 6 seconds

Learn more on time of flight here;

https://brainly.com/question/1088602

Otras preguntas

Q&A Education