document.write( "Question 1166876: A toy rocket is shot vertically into the air from a launching pad 9 feet above the ground with an initial velocity of 64 feet per second. The height h, in feet, of the rocket above the ground at t seconds after launch is given by the function h(t)= -16t^+64t+9. How long will it take the rocket to reach its maximum height? What is the maximum height? \r
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Algebra.Com's Answer #791426 by ikleyn(52781) $\"\"$ $\"About$

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A toy rocket is shot vertically into the air from a launching pad 9 feet above the ground with an initial velocity
\n" ); document.write( "of 64 feet per second. The height h, in feet, of the rocket above the ground at t seconds after launch is given by the
\n" ); document.write( "function h(t)= -16t^+64t+9. How long will it take the rocket to reach its maximum height? What is the maximum height?
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document.write( "The function  H(t) = -16t^2 + 64t + 9  is a quadratic function, whose plot is a parabola opened down.\r\n" );
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document.write( "This quadratic function has the maximum at the value of its argument  t = , where \"a\" is the coefficient at t^2\r\n" );
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document.write( "and \"b\" is the coefficient at t.\r\n" );
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document.write( "In your case, a= -16,  b= 64, so the function gets the maximum at  t =  = 2 seconds.\r\n" );
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document.write( "So, the ball gets the maximum height  2 seconds after is hit straight up. \r\n" );
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document.write( "The maximum height is  H(t) = -16*2^2 + 64*2 + 9 =  73 ft.       ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "On finding the maximum/minimum of a quadratic function, see the lessons \r
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\n" ); document.write( "\n" ); document.write( "    - Briefly on finding the minimum/maximum of a quadratic function\r
\n" ); document.write( "\n" ); document.write( "    - HOW TO complete the square to find the vertex of a parabola\r
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\n" ); document.write( "\n" ); document.write( "On solving similar problems to yours in this post, see the lessons\r
\n" ); document.write( "\n" ); document.write( "    - Problem on a projectile moving vertically up and down\r
\n" ); document.write( "\n" ); document.write( "    - Problem on an arrow shot vertically upward\r
\n" ); document.write( "\n" ); document.write( "    - Problem on a ball thrown vertically up from the top of a tower \r
\n" ); document.write( "\n" ); document.write( "    - Problem on a toy rocket launched vertically up from a tall platform\r
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