document.write( "Question 173551: A Parabola with the equation \"y=ax%5E2\" passes through three vertices of a square. if the area of the square = 18, find the value of \"a\" in \"y=ax%5E2\". \n" ); document.write( "
Algebra.Com's Answer #128436 by Edwin McCravy(20060)\"\" \"About 
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A Parabola with the equation \"y=ax%5E2\" passes through three vertices of a square. if the area of the square = 18, find the value of \"a\" in \"y=ax%5E2\".
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document.write( "The formula for the area of a square, where \"s\" \r\n" );
document.write( "is the length of each side is \r\n" );
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document.write( "\"A+=+s%5E2\"\r\n" );
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document.write( "Substitute 18 for A\r\n" );
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document.write( "\"18+=+s%5E2\"\r\n" );
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document.write( "Take square roots of both sides\r\n" );
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document.write( "\"sqrt%2818%29=sqrt%28s%5E2%29\"\r\n" );
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document.write( "\"sqrt%2818%29=s\"\r\n" );
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document.write( "So each side is \"sqrt%2818%29\"\r\n" );
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document.write( "We draw the square:\r\n" );
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document.write( "Let's draw a diagonal:\r\n" );
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document.write( "Use the Pythagorean theorem to find the length \r\n" );
document.write( "of the diagonal:\r\n" );
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document.write( "\"diagonal%5E2=+%28sqrt%2818%29%29%5E2+%2B+%28sqrt%2818%29%29%5E2\"\r\n" );
document.write( "\"diagonal%5E2=+18%2B18\"\r\n" );
document.write( "\"diagonal%5E2=36\"\r\n" );
document.write( "Taking square roots:\r\n" );
document.write( "\"diagonal=6\"\r\n" );
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document.write( "Now since the diagonal is 6, let's tilt the square\r\n" );
document.write( "45° and put the diagonal along the y-axis with a \r\n" );
document.write( "corner at the origin, like this: \r\n" );
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document.write( "We draw the other diagonal:\r\n" );
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document.write( "Since the vertical diagonal is 6 units,\r\n" );
document.write( "so is the horizontal diagonal, so\r\n" );
document.write( "the two vertices at the end of the\r\n" );
document.write( "horizontal diagonal are \"matrix%281%2C1%2C%22%283%2C3%29%22%29\"\r\n" );
document.write( "and \"matrix%281%2C1%2C%22%28-3%2C3%29%22%29\" \r\n" );
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document.write( "We put the coordinates at these corners:\r\n" );
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document.write( "Now we can roughly sketch in the parabola\r\n" );
document.write( "we are looking for:\r\n" );
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document.write( "We put the coordinates at these corners:\r\n" );
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document.write( "Since the parabola has the form \"y=ax%5E2\",\r\n" );
document.write( "and goes through \"matrix%281%2C1%2C%22%283%2C3%29%22%29\", \r\n" );
document.write( "we substitute \"x=3\" and \"y=3\"\r\n" );
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document.write( "\"y=ax%5E2\"\r\n" );
document.write( "\"3=a%283%29%5E2\"\r\n" );
document.write( "\"3=a%289%29\"\r\n" );
document.write( "\"3=9a\"\r\n" );
document.write( "\"3%2F9=a\"\r\n" );
document.write( "\"1%2F3=a\"  \r\n" );
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document.write( "The value of \"a\" is therefore \"1%2F3\" and\r\n" );
document.write( "the equation of the parabola is\r\n" );
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document.write( "\"y=1%2F3\"\"x%5E2\"  \r\n" );
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document.write( "Edwin
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