document.write( "Question 297565: Graph the quadratic function
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document.write( "f(x) = -x2 + 1
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document.write( "Describe the correct graph and why...Which way does the parabola go up or down, where does the graph cross the x-axis and y-axis....
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Algebra.Com's Answer #214273 by Theo(13342)![]() ![]() You can put this solution on YOUR website! Graph the quadratic function \n" ); document.write( "f(x) = -x^2 + 1 \n" ); document.write( "Describe the correct graph and why...Which way does the parabola go up or down, where does the graph cross the x-axis and y-axis....\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The graph points up and opens down.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Standard form of quadratic equation is ax^2 + bx + c = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Set f(x) = to 0 and you have this equation in standard form.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-x^2 + 1 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In this equation:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "a = -1 \n" ); document.write( "b = 0 \n" ); document.write( "c = 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Maximum point is at x = -b/2a which becomes 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When x = 0, y = 1, so the maximum point is (x,y) = (0,1).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "To find the points where this graph crosses the x-axis, you have to solve the equation -x^2 + 1 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "With this equation, you subtract 1 from both sides of the equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-x^2 = -1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Multiply both sides of this equation by -1 to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x^2 = 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Take the square root of both sides of this equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = +/- 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Those should be the x-axis crossing points.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You could also have factored the equation of -x^2 + 1 = 0 to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(-x+1) * (x+1) = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When either of these factors = 0, the equation is grue, so you set each of the factors equal to 0 and solve.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = -1 and x = 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You graph this equation by plotting some values of x and getting corresponding values of y.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You start with x = -1, x = 0, x = 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "That should be enough to draw a rough graph, but you might want to fill in some additional points to fit the curve better.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Your graph should look like this:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |