document.write( "Question 395288: An Olympic ski jumper skis off a spring board. Her height h, in meters, above the ground, t seconds after she jumps, is given by h(t)= -4.9t^2 + 20t +15. Algebraically determine the approximate instantaneous rate of change in her height at 2 seconds and describe what is happening at that time. \n" ); document.write( "
Algebra.Com's Answer #280701 by ankor@dixie-net.com(22740)\"\" \"About 
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An Olympic ski jumper skis off a spring board. Her height h, in metres, above
\n" ); document.write( " the ground, t seconds after she jumps, is given by h(t)= -4.9t^2 + 20t +15.
\n" ); document.write( " Algebraically determine the approximate instantaneous rate of change in her
\n" ); document.write( " height at 2 seconds and describe what is happening at that time.
\n" ); document.write( ":
\n" ); document.write( "A good way to see what is happening is to graph this equation
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-4%2C+6%2C+-10%2C+50%2C+-4.9x%5E2%2B20x%2B15%29+\"
\n" ); document.write( ":
\n" ); document.write( "It looks like it is at max height at 2 sec,
\n" ); document.write( " prove that with the axis of symmetry formula x = -b/(2a), where a = -4.9, b=20
\n" ); document.write( "x = \"%28-20%29%2F%282%2A-4.9%29\"
\n" ); document.write( "x = \"%28-20%29%2F%28-9.8%29\"
\n" ); document.write( "x = 2.04 sec it is at max height
\n" ); document.write( ":
\n" ); document.write( "At this point it is changing from an upward path to a downward path
\n" ); document.write( "There is no change in height at 2 sec \n" ); document.write( "
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