document.write( "Question 154221: For the function y = 3x^2 + 12x + 9 find:\r
\n" );
document.write( "\n" );
document.write( "A. Whether the curve is concave up or down\r
\n" );
document.write( "\n" );
document.write( "B. The y-intercept\r
\n" );
document.write( "\n" );
document.write( "C. The x-intercept\r
\n" );
document.write( "\n" );
document.write( "D. The Vertex\r
\n" );
document.write( "\n" );
document.write( "E. The Maximum or Minimum value.
\n" );
document.write( " \n" );
document.write( "
Algebra.Com's Answer #113531 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! y = 3x^2 + 12x + 9 ... Start with the given equation.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y' = 6x + 12 ... Find the first derivative\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y'' = 6 ... Find the second derivative \r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Since y'' is always positive, this means that the function is concave up.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "b)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Y-Intercept:\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( " \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( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the y-intercept is (0,9)\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "----------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "c)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "X-Intercept(s):\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( "Notice we have a quadratic equation in the form of \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for x\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( " \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( " \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( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the answers are \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "So the x-intercepts are (-1,0) and (-3,0)\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "----------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "d)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Vertex:\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In order to find the vertex, we first need to find the x-coordinate of the vertex.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "To find the x-coordinate of the vertex, use this formula: \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "From \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( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the x-coordinate of the vertex is \n" ); document.write( " \n" ); document.write( " \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 \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( " \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( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the y-coordinate of the vertex is \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the vertex is \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "----------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "e)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Maximum or Minimum value:\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Since the function is concave up, this means that the function has a minimum. The max/min value correspond to the y coordinate of the vertex. So the minimum value is \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-----------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Here's a graph to verify our answers:\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " |