solving a word problem using a quadratic equation with irrational roots

Mathematics
Tutor: None Selected Time limit: 1 Day

A ball is thrown from an initial height of 

 meter with an initial upward velocity of 
. The ball's height 
 (in meters) after 
 seconds is given by the following 

h=1 plus  25 t subtract 5t exponent 2 

Find all values of 
 for which the ball's height is 
 meters.
Apr 30th, 2015

See attached file.

Hope it helps!

solution.pdf 




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Apr 30th, 2015

yes it helped very much could you also help me with this ? 

A model rocket is launched with an initial upward velocity of 

202/fts

. The rocket's height 

h

 (in feet) after 

t

 seconds is given by the following.

h=202t-16t2

Find all values of 

t

 for which the rocket's height is 

82

 feet.

Round your answer(s) to the nearest hundredth

Apr 30th, 2015

Put 82 in for h

82 = 202t - 16 t^2

subtract 82 and put it in the right form:

16t^2 - 202t + 82 = 0

To make the math easier, we can divide everything by 2

8t^2 - 101t + 41 = 0;  that gives us a=8, b=(-101), and c = 41 for the quadratic formula.

Apr 30th, 2015

that confuses me a bit

Apr 30th, 2015

Okay,

Which part was confusing?


Apr 30th, 2015

How do you get the decimal 

Apr 30th, 2015

Plug the numbers (a, b, and c) into the quadratic formula and solve.  


Apr 30th, 2015

okay so i got 12.205 and 0.4199 could you help me round it to the nearest hundreths and check if its right first please

Apr 30th, 2015

you there ?


Apr 30th, 2015

Yes, I'm here.  Let me check...


Apr 30th, 2015

I got 13.02 and -0.39  (however, the negative value will not work in this case.)

Apr 30th, 2015

could you help me set it up to get the right number for the square root cause i got -751 with positive 38 but with -38 i got 769 i confuse my signs when im supposed solve the 4*ac part

A ball is thrown from a height of 

38

 meters with an initial downward velocity of 

3/ms

. The ball's height 

h

 (in meters) after 

t

 seconds is given by the following.

h=38−3t-5t2

How long after the ball is thrown does it hit the ground?Round your answer(s) to the nearest hundredth.

Apr 30th, 2015

I'm sorry, I am in the middle of something right now. I cannot help with any additional problems at this time.

Apr 30th, 2015

okay thank you

Apr 30th, 2015

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Apr 30th, 2015
Dec 7th, 2016
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