Word Problem

[clinton]

Throwing a wrench. An angry construction worker throws
his wrench downward from a height of 128 feet with an
initial velocity of 32 feet per second. The height of the
wrench above the ground after t seconds is given
by S(t) = -16t2 - 32t + 128.
a) What is the height of the wrench after 1 second?
b) How long does it take for the wrench to reach the
ground?

 

[clinton]

I am having a bit of problem. I think it should be A^2+b^2=c^2
The confusing part is plugging the numbers.

 

[Denis]

Quit fooling around, Clinton :wink:

Is that 2 separate problems? BE CLEAR :shock:

 

[Deleted member 4993]

I am having a bit of problem. I think it should be A^2+b^2=c^2

How did you come to that conclusion?

The confusing part is plugging the numbers.

 

[clinton]

Okay, I can factor it and solve example -16t^2 -32t +128.
4(4t^2 - 8t +32)
(2t+4)(2t-8)
2t +4 = 0
2t = -4
t =-2

2t -8 = 0
2t = 8
t = 4

 

[Deleted member 4993]

Okay, I can factor it and solve example -16t^2 -32t +128.
4(4t^2 - 8t +32)
(2t+4)(2t-8) <<< How did you get that ???

s = -16t[sup:3ab5j1ci]2[/sup:3ab5j1ci] -32t + 128 = -16 (t[sup:3ab5j1ci]2[/sup:3ab5j1ci] + 2t -8) = -16(t+4)(t-2)

Now what happens at those t's?
2t +4 = 0
2t = -4
t =-2

2t -8 = 0
2t = 8
t = 4