document.write( "Question 430208: A projectile is thrown upward so that its distance above the ground after t seconds is h=-15t(squared)+390t. After how many seconds does it reach its maximum height? \n" ); document.write( "

Algebra.Com's Answer #298767 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

 
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document.write( "h = -15t^2+390t   |parabola opening downward
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document.write( "h = -15[(t-13)^2 -169]  |completing square to find the Vertex
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document.write( "h = -15(t-13)^2 +2535
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document.write( "In 13 sec it reaches it's maximum height \n" );
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