document.write( "Question 58872: Really stuck on this one! For the quadratic function y =F(x) = x^2-2x-15
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Algebra.Com's Answer #40381 by Edwin McCravy(20055)\"\" \"About 
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document.write( "Really stuck on this one! For the quadratic \r\n" );
document.write( "function y  = f(x) = x^2-2x-15 i need the \r\n" );
document.write( "vertex and x & Y intercepts, graph, domain \r\n" );
document.write( "& range..thank you so much,  Carol\r\n" );
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document.write( "The x-coordinate of the vertex of the parabola \r\n" );
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document.write( "          y = f(x) = ax² + bx + c \r\n" );
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document.write( "is h = -b/(2a)\r\n" );
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document.write( "And the y-coordinate of the vertex is\r\n" );
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document.write( "k = f(h)\r\n" );
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document.write( "Its domain is (-¥, ¥)\r\n" );
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document.write( "and the range is \r\n" );
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document.write( "[k, ¥)  if a > 0\r\n" );
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document.write( "and \r\n" );
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document.write( "(-i, k]  if a < 0\r\n" );
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document.write( "The y-intercept is (0, c)\r\n" );
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document.write( "The x intercepts are the (r1,0), (r2,0)\r\n" );
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document.write( "where r1 and r2 are the solutions to the\r\n" );
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document.write( "equation ax² + bx + c = 0 if they are \r\n" );
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document.write( "real numbers.  If they are imaginary\r\n" );
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document.write( "numbers there are no x intercepts.\r\n" );
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document.write( "Your problem is y = f(x) = x² - 2x - 15\r\n" );
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document.write( "so a = 1, b = -2, c = -15 \r\n" );
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document.write( "The x-coordinate of the vertex of the parabola \r\n" );
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document.write( "          y = f(x) = x² - 2x - 15 \r\n" );
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document.write( "is h = -b/(2a) = -(-2)/[2(1)] = 1\r\n" );
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document.write( "And the y-coordinate of the vertex is\r\n" );
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document.write( "k = f(h) = f(1) = (1)² - 2(1) - 15 = -16\r\n" );
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document.write( "So the vertex is (h, k) = (-1, -16)\r\n" );
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document.write( "Its domain is (-¥, ¥)\r\n" );
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document.write( "and the range is \r\n" );
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document.write( "[k, ¥)  if a > 0\r\n" );
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document.write( "and since a = 1, which is > 0 and k = -16 the \r\n" );
document.write( "range is [-16, ¥	)\r\n" );
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document.write( "The y-intercept is (0, c)\r\n" );
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document.write( "and since c = -15, the y-intercept is (0, -15)\r\n" );
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document.write( "The x intercepts are (r1,0), (r2,0)\r\n" );
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document.write( "where r1 and r2 are the solutions to the\r\n" );
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document.write( "equation ax² + bx + c = 0 if they are \r\n" );
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document.write( "real numbers.  \r\n" );
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document.write( "Solve this equation: \r\n" );
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document.write( " x² - 2x - 15 = 0\r\n" );
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document.write( "you will get solutions -3 and 5 \r\n" );
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document.write( "so the x-intercepts are (-3,0) and (5,0)\r\n" );
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document.write( "The graph is:\r\n" );
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document.write( "\"+graph%28+300%2C+300%2C+-11%2C+13%2C++-20%2C+3%2C+x%5E2-2x-15%29+\"  \r\n" );
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document.write( "Edwin
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