document.write( "Question 1139880: A model rocket is launched with an initial velocity of 160 ft/s. The height, h, in feet, of the rocket t seconds after the launch is given by
\n" ); document.write( "h = −16t2 + 160t.
\n" ); document.write( " How many seconds after launch will the rocket be 380 ft above the ground? Round to the nearest hundredth of a second. \n" ); document.write( "

Algebra.Com's Answer #760372 by ikleyn(52799) $\"\"$ $\"About$

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document.write( "It will be at the given height when  h(t) = 380,  or, equivalently,\r\n" );
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document.write( "     = 380\r\n" );
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document.write( "     = 0.\r\n" );
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document.write( "Solve this quadratic equation\r\n" );
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document.write( "     =  = .\r\n" );
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document.write( "There are two solution, both make sense,  =  = 3.88 seconds in the increasing part of the parabola,\r\n" );
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document.write( "and   =  = 6.12 seconds in the decreasing branch of the parabola.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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