A frusmtum of a pyramid is 16cm square at the bottom,6cm at the top,12cm high. find the volume of the frustum. ​

A frustum of a pyramid is 16 cm square at the bottom ,6 cm square at the top ,and 12 cm high.Find the volume of the frustum

Step-by-step explanation:

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.