document.write( "Question 149906: If a soccer ball is kicked straight up from the ground with an initial velocity of 32 feet per second, then its height above the earth in feet is given by s(t) = -16t^2 + 32t, where t is time in seconds. What is the maximum height reached by the ball? Graph parabola 0<=t<=2 \n" ); document.write( "
Algebra.Com's Answer #110032 by jim_thompson5910(35256)\"\" \"About 
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The maximum height occurs at the vertex of the parabola. So let's find the vertex first\r
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\n" ); document.write( "\n" ); document.write( "In order to find the vertex, we first need to find the x-coordinate of the vertex.\r
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\n" ); document.write( "\n" ); document.write( "To find the x-coordinate of the vertex, use this formula: \"x=%28-b%29%2F%282a%29\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=%28-b%29%2F%282a%29\" Start with the given formula.\r
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\n" ); document.write( "\n" ); document.write( "From \"y=-16t%5E2%2B32t\", we can see that \"a=-16\", \"b=32\", and \"c=0\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=%28-%2832%29%29%2F%282%28-16%29%29\" Plug in \"a=-16\" and \"b=32\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=%28-32%29%2F%28-32%29\" Multiply 2 and \"-16\" to get \"-32\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=1\" Divide.\r
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\n" ); document.write( "\n" ); document.write( "So the x-coordinate of the vertex is \"x=1\". Note: this means that the axis of symmetry is also \"x=1\".\r
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\n" ); document.write( "\n" ); document.write( "Now that we know the x-coordinate of the vertex, we can use it to find the y-coordinate of the vertex.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16t%5E2%2B32t\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16t%5E2%2B32t\" Plug in \"x=1\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16t%5E2%2B32t\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16%281%29%5E2%2B32%281%29\" Plug in \"t=1\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16%281%29%2B32%281%29\" Square \"1\" to get \"1\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16%2B32%281%29\" Multiply \"-16\" and \"1\" to get \"-16\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=-16%2B32\" Multiply \"32\" and \"1\" to get \"32\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=16\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "So the y-coordinate of the vertex is \"y=16\".\r
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\n" ); document.write( "\n" ); document.write( "So the vertex is .\r
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\n" ); document.write( "\n" ); document.write( "So the max height is 16 feet.\r
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\n" ); document.write( "\n" ); document.write( "Now if we graph the equation \"y=-16t%5E2%2B32t\" on the interval , we can see that the highest point is (1,16). So this confirms our answer.\r
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\n" ); document.write( "\n" ); document.write( "\"Photobucket Graph of \"y=-16t%5E2%2B32t\"\r
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