document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1111306>Question 1111306</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Determine the quadratic function f whose graph is given.<BR>\n" );
document.write( "The vertex is (2, -8) and the y-intercept is -4.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #726288 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=726288\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Determine the quadratic function f whose graph is given.<BR>\n" );
document.write( "The vertex is (2, -8) and the y-intercept is -4.<BR>\n" );
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document.write( "Form:: y = ax^2 + bx + c<BR>\n" );
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document.write( "Note:: f(0) = c and f(0) = -4, so c = -4<BR>\n" );
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document.write( "Using (2,-8) you get -8 = a(2^2)+b(2)-4<BR>\n" );
document.write( "-4 = 4a + 2b<BR>\n" );
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document.write( "Note:: The vertex occurs where x = -b/(2a)<BR>\n" );
document.write( "So, -b/2a = 2<BR>\n" );
document.write( "Then -b = 4a<BR>\n" );
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document.write( "You now have 2 equations in a and b; solve them by substitution::<BR>\n" );
document.write( "-4 = -b + 2b<BR>\n" );
document.write( "b = -4<BR>\n" );
document.write( "Then a = 1<BR>\n" );
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document.write( "Equation:: y = x^2 -4x -4<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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