document.write( "Question 1177659: Background info: In this task, you will practice finding the area under a nonlinear function by using rectangles. You will use graphing skills in addition to the knowledge gathered in this unit. Sketch the graph of the function y = 20x − x2, and approximate the area under the curve in the interval [0, 20] by dividing the area into the given numbers of rectangles.\r
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Algebra.Com's Answer #806770 by MathLover1(20850)\"\" \"About 
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Sketch the graph of the function \"y+=+20x-x%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"graph%28+600%2C+600%2C+-10%2C+35%2C+-10%2C+110%2C+20x-x%5E2%29+\"\r
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\n" ); document.write( "\n" ); document.write( "divide the area in \"10\" rectangles \r
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\n" ); document.write( "\n" ); document.write( "In order to figure the width of each rectangle we can use the following formula:\r
\n" ); document.write( "\n" ); document.write( " Δ \"x=%28b-a%29%2Fn\"\r
\n" ); document.write( "\n" ); document.write( "in this case \"a=0\",\"+b=20\" and \"n=10\" so we get:\r
\n" ); document.write( "\n" ); document.write( "Δ \"x=%2820-0%29%2F10=2\"\r
\n" ); document.write( "\n" ); document.write( "so \"each\" rectangle must have a \"width\" of \"2+\"units\r
\n" ); document.write( "\n" ); document.write( "We can now calculate the height of each rectangle. So we figure the y-value of each corner of the rectangles. We get the following heights:\r
\n" ); document.write( "\n" ); document.write( "\"h%5B1%5D=36\" ..........\"x=2+\"units->\"y+=+20%2A2-2%5E2=36\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B2%5D=64\"..............\"x=4+\"units->\"y+=+20%2A4-4%5E2=64\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B3%5D=84\".............\"x=6+\"units->\"y+=+20%2A6-6%5E2=84\"...and so on\r
\n" ); document.write( "\n" ); document.write( "\"h%5B4%5D=+96\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B5%5D=100\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B6%5D=96\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B7%5D=84\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B8%5D=64\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B9%5D=36\"\r
\n" ); document.write( "\n" ); document.write( "\"h%5B10%5D=0\"\r
\n" ); document.write( "\n" ); document.write( "so now we can use the following formula to find the area under the graph. Basically what the formula does is add the areas of the rectangles:\r
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\n" ); document.write( "\n" ); document.write( "\"A=2%2836%2B64%2B84%2B96%2B100%2B96%2B84%2B64%2B36%2B0%29\"\r
\n" ); document.write( "\n" ); document.write( "\"A=1320\" -> approximate the area under the curve in the interval [\"0\", \"20\"] \r
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