document.write( "Question 1016037: A science teacher is conducting an experiment with a model rocket. The function h=-16t^2+64t models the height of the rocket, where h is the height of the rocket in feet and t is the time in seconds after it is launched. Determine how many seconds the rocket is in the air. \n" ); document.write( "

Algebra.Com's Answer #632414 by macston(5194) $\"\"$ $\"About$

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\n" ); document.write( "Set h=0. The rocket will be at 0 height twice:
\n" ); document.write( "once when launched (t=0) and again when it lands.
\n" ); document.write( "You want the difference between these two.
\n" ); document.write( ".
\n" ); document.write( " $\"-16t%5E2%2B64t=0\"$
\n" ); document.write( " $\"t%28-16t%2B64%29=0\"$
\n" ); document.write( " $\"t=0\"$ $\"OR\"$ $\"-16t%2B64=0\"$
\n" ); document.write( " $\"t=0\"$ $\"OR\"$ $\"-16t=-64\"$
\n" ); document.write( " $\"t=0\"$ $\"OR\"$ $\"t=4\"$
\n" ); document.write( ".
\n" ); document.write( "The rocket is launched at 0 seconds and lands at 4 seconds.
\n" ); document.write( ".
\n" ); document.write( "ANSWER: The rocket is in the air for 4 seconds.
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