Amodel rocket is launched from a raised platform at a speed of 144 feet per second. its height in feet is given by h( t) = -16 t 2 + 144 t + 20 ( t = seconds after launch). after how many seconds does the object reach its maximum height?

after 4.5 seconds

Step-by-step explanation:

Given the eqn of the height reached by the rocket.

h(t)= -16t^2 +144t +20

Note: at the maximum height dh(t)/dt = 0

Therefore, differentiating the eqn of height.

dh(t)/dt = -32t + 144

Equating dh(t)/dt to zero, we have.

-32t+144=0

32t=144

t = 144/32

t = 4.5 seconds

the answer is a

step-by-step explanation:

answer:

total cost for tiles and paints is $924.  

step-by-step explanation:

we have been given that a community hall is in the shape of a cuboid. the hall is 40m long 15m high and 3m wide.

the paint will be required for 4 walls and ceiling.

let us find area of walls and ceiling.

therefore, the area of walls and ceiling is 1410 square meters.

given: cost for 10 litre of paint is $10 and 10 litre paint covers 25 square meter. therefore,

therefore, the total painting cost is $564.

tiles will be required for floor. let us find the area of floor.

given: 1m squared floor tiles costs $3. so,

therefore, the total tiles cost is $360.

now let us find combined total cost of tiles and paint.

therefore, the combined total cost of tiles and paint is $924.