document.write( "Question 701011: Can someone please help me. I don't understand how to start these. \r
\n" ); document.write( "\n" ); document.write( "1. For the given equation, list the intercepts and test for symmetry.
\n" ); document.write( "y=x^2-5x-6\r
\n" ); document.write( "\n" ); document.write( "2. Write the equation of the circle in standard form.  Find the center, radius, intercepts, and graph the
\n" ); document.write( "circle.
\n" ); document.write( "x^2+y^2+14x-12y=-76
\n" ); document.write( "

Algebra.Com's Answer #432220 by KMST(5328)\"\" \"About 
You can put this solution on YOUR website!
1. \"y=x%5E2-5x-6\" can be called a quadratic function and graphs as a parabola opening up. (It's shaped like a smile).
\n" ); document.write( "
\n" ); document.write( "Intercepts are the points where the graph representing that equation crosses the x-axis and the y-axis.
\n" ); document.write( "The x-axis is the set of all the points with \"y=0\".
\n" ); document.write( "Making \"y=0\" we find the x-intercepts:
\n" ); document.write( "\"0=x%5E2-5x-6\" --> \"0=%28x-6%29%28x%2B1%29\" (factoring)
\n" ); document.write( "has a solution when \"x-6=0\" --> \"highlight+%28x=6%29\" and
\n" ); document.write( "a solution when \"x%2B1=0\" --> \"highlight%28x=-1%29\"
\n" ); document.write( "The y-axis is the set of all the points with \"x=0\" .
\n" ); document.write( "Making \"x=0\" we find the y-intercept:
\n" ); document.write( "\"y=0%5E2-5%2A0-6\" --> \"y=0-1-6\" --> \"highlight%28y=-6%29\"
\n" ); document.write( "
\n" ); document.write( "When teachers say to test for SYMMETRY they usually want you to find out, without graphing,
\n" ); document.write( "if the graph representing the equation has symmetry.
\n" ); document.write( "Maybe the side to the right of the y-axis is a mirror image of the left side.
\n" ); document.write( "Or maybe the side above of the x-axis is a mirror image of side below the x-axis.
\n" ); document.write( "Or maybe every point has a reflection on the other side of the origin.
\n" ); document.write( "To find out, you change \"x\" to \"-x\",
\n" ); document.write( "or \"y\" to \"-y\",
\n" ); document.write( "or (x,y) to (-x,-y),
\n" ); document.write( "and see if you end up with the same equation.
\n" ); document.write( "For \"y=x%5E2-5x-6\", any of those changes gives you a different equation.
\n" ); document.write( "The graph for \"y=x%5E2-5x-6\" has an axis of symmetry, but it is neither the x-axis, not the y-axis.
\n" ); document.write( "
\n" ); document.write( "Knowing that a graph will be symmetrical before you start graphing, makes graphing easier.
\n" ); document.write( "In pictures,
\n" ); document.write( "\"graph%28100%2C100%2C-5%2C5%2C-5%2C5%2Cx%5E2%2F3%29\" is a function with symmetry about the y-axis because it has the same y for \"x\" and \"-x\" ( f(x)=f(-x) }
\n" ); document.write( "\"x%5E2-6x%2By%5E2=0\" graphs as \"drawing%28100%2C100%2C-2%2C8%2C-5%2C5%2Cgrid%281%29%2Cblue%28circle%283%2C0%2C3%29%29%29\" and has symmetry about the x-axis, because for \"y\" and for \"-y\" the equation is the same.
\n" ); document.write( "\"x%5E2%2By%5E2=16\" \"drawing%28100%2C100%2C-6%2C6%2C-6%2C6%2Cgrid%281%29%2Cblue%28circle%280%2C0%2C4%29%29%29\" and \"xy=1\" \"graph%28100%2C100%2C-5%2C5%2C-5%2C5%2C1%2Fx%29\"
\n" ); document.write( "have symmetry about the origin because the equation is the same for point (x,y) as for point (-x,-y).
\n" ); document.write( "
\n" ); document.write( "2. \"x%5E2%2By%5E2%2B14x-12y=-76\" --> \"x%5E2%2B14x%2By%5E2-12y=-76\" --> \"x%5E2%2B14x%2B49%2By%5E2-12y%2B36=-76%2B49%2B36\" --> \"%28x%5E2%2B14x%2B49%29%2B%28y%5E2-12y%2B36%29=9\" --> \"highlight%28%28x%2B7%29%5E2%2B%28y-6%29%5E2=3%5E2%29\"
\n" ); document.write( "That equation is true for all the points (x,y) that are at distance 3 from point (-7,6).
\n" ); document.write( "That is the equation of a circle with radius 3, centered at the point (-7,6),
\n" ); document.write( "with \"x=-7\" and \"y=6\".
\n" ); document.write( "The center is too far below the x-axis compared to the radius, so the circle does not cross the x-axis, and there are no x-intercepts.
\n" ); document.write( "The same thing happens with the y-axis. The center is too far to the right. There is no y-intercept.
\n" ); document.write( "
\n" );