document.write( "Question 255656: what is x^2 -4 = x
\n" ); document.write( "we're doing 'solving equations graphically? \n" ); document.write( "

Algebra.Com's Answer #187889 by Edwin McCravy(20055) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"x%5E2+-4+=+x\"$
\n" ); document.write( "

\r\n" );
document.write( "Get 0 on the right by adding -x to both sides:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Let y=0\r\n" );
document.write( "\r\n" );
document.write( "Then we can write the above as this system of equations:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Now we draw the graph of the first equation by getting\r\n" );
document.write( "some points:\r\n" );
document.write( "\r\n" );
document.write( " x | y\r\n" );
document.write( "------\r\n" );
document.write( "-3 | 8\r\n" );
document.write( "-2 | 2\r\n" );
document.write( "-1 |-2\r\n" );
document.write( " 0 |-4\r\n" );
document.write( " 1 |-4\r\n" );
document.write( " 2 |-2 \r\n" );
document.write( " 3 | 2\r\n" );
document.write( " 4 | 8\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Draw a smooth curve through those points\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "   \r\n" );
document.write( "Now the graph of the other equation in the system, y=0,\r\n" );
document.write( "is simply the x-axis, so we only need to know the points where\r\n" );
document.write( "the graph intersects the x-axis.=, and they will be the\r\n" );
document.write( "solutions to the system\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Notice that they cross at the short green lines below:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The x-intercept on the left is a little more than half way between\r\n" );
document.write( "-1 and -2, so \"guess\"timate it to be -1.6.\r\n" );
document.write( "\r\n" );
document.write( "The x-intercept on the right is a little more than half way between\r\n" );
document.write( "2 and 3, so \"guess\"timate it to be 2.6.\r\n" );
document.write( "\r\n" );
document.write( "So the solutions are about x = -1.6 and x = 2.6.\r\n" );
document.write( "\r\n" );
document.write( "Edwin

\n" ); document.write( "

\n" );