Two word problems  TOPIC_SOLVED

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.

Two word problems

Postby Writ on Tue Oct 23, 2012 5:34 pm

Can anyone explain how to work these? I'm completely lost. Thanks!

1. An object is launched from a platform that is 256 feet above the ground. The height, s, of the
object above the ground t seconds after it is launched is given by the formula s = -16t^2 + 96t + 256

a) What is the height of the object after 2 seconds?
b) How long will it take for the object to hit the ground?
c) When will the object be at a height of 256 feet?

2. A homeowner has installed an in-ground pool in the backyard. The pool is rectangular in
shape, with a length that is 4 feet more than its width. The homeowner put a one-foot-wide concrete
border around the pool. If the area covered by the pool and the border is 96 square feet, find the
dimensions of the pool.
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Re: Two word problems  TOPIC_SOLVED

Postby little_dragon on Tue Oct 23, 2012 7:48 pm

Writ wrote:Can anyone explain how to work these? I'm completely lost. Thanks!

1. An object is launched from a platform that is 256 feet above the ground. The height, s, of the
object above the ground t seconds after it is launched is given by the formula s = -16t^2 + 96t + 256

a) What is the height of the object after 2 seconds?
b) How long will it take for the object to hit the ground?
c) When will the object be at a height of 256 feet?

a) plug in the number they give you for t and solve for s
b) plug in the height s=0 for "the ground" and solve for t
c) plug in the number for height and solve for t
they show U here: http://www.purplemath.com/modules/quadprob.htm

Writ wrote:2. A homeowner has installed an in-ground pool in the backyard. The pool is rectangular in
shape, with a length that is 4 feet more than its width. The homeowner put a one-foot-wide concrete
border around the pool. If the area covered by the pool and the border is 96 square feet, find the
dimensions of the pool.

draw a picture w/ 2 rectangles (1 inside the other)
label w/ w, w+4, w+1+1, w+4+1+1
do area eqn
set equal to 96
solve
its like what they show halfway down here: http://www.purplemath.com/modules/perimetr2.htm
but w/ rectangles instead of circles

plz rite back if ur stuck
thx
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