document.write( "Question 916626: The height h in feet of an object thrown upward from a height of 5 feet, with an initial velocity of 30 feet per second, is given by the equation h=-16t^2+30t+5, where h represents the height of the object after t seconds. How long will it take the object to hit the ground? \n" ); document.write( "

Algebra.Com's Answer #556207 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"+h+=+-16t%5E2+%2B+30t+%2B+5+\"$
\n" ); document.write( "When the object hits the ground, the
\n" ); document.write( "height above ground = zero, so
\n" ); document.write( " $\"+h+=+0+\"$
\n" ); document.write( " $\"+-16t%5E2+%2B+30t+%2B+5+=+0+\"$
\n" ); document.write( "Solve using the quadratic formula
\n" ); document.write( " $\"+h+=+%28+-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"$
\n" ); document.write( " $\"+a+=+-16+\"$
\n" ); document.write( " $\"+b+=+30+\"$
\n" ); document.write( " $\"+c+=+5+\"$
\n" ); document.write( " $\"+t+=+%28+-30+%2B-+sqrt%28+30%5E2+-+4%2A%28-16%29%2A5+%29%29+%2F+%282%2A%28-16%29%29+\"$
\n" ); document.write( " $\"+t+=+%28+-30+%2B-+sqrt%28+900+%2B+320+%29%29+%2F+%28-32%29%29+\"$
\n" ); document.write( " $\"+t+=+%28+-30+%2B-+sqrt%28+1220+%29%29+%2F+%28-32%29%29+\"$
\n" ); document.write( " $\"+t+=+%28+-30+-+34.928%29+%2F+%28-32%29%29+\"$
\n" ); document.write( "( The positive root does not work here )
\n" ); document.write( " $\"+t+=+%28+-64.928+%29+%2F+%28+-32+%29+\"$
\n" ); document.write( " $\"+t+=+2.029+\"$
\n" ); document.write( "The object hits the ground in 2.029 sec
\n" ); document.write( "Here's the plot:
\n" ); document.write( " $\"+graph%28+400%2C+400%2C+-1%2C+3%2C+-2%2C+20%2C+-16x%5E2+%2B+30x+%2B+5+%29+\"$
\n" ); document.write( " \n" ); document.write( "

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