document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=805950>Question 805950</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the value of a, given that the maximum value of f(x)=ax^2 +3x-4 is 5.\r<BR>\n" );
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document.write( "I'm very confused on how to do this problem. Please help! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #485671 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=485671\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the value of a, given that the maximum value of f(x)=ax^2 +3x-4 is 5. <BR>\n" );
document.write( "This equation is that of a parabola with a maxmum value of 5(parabola opens down)<BR>\n" );
document.write( "Its standard(vertex) form of equation: y=-a(x-h)^2+k, (h,k)=(x,y) coordinates of the vertex, with k=maximum.<BR>\n" );
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document.write( "convert given equation to vertex form:<BR>\n" );
document.write( "Complete the square:<BR>\n" );
document.write( "y=ax^2 +3x-4<BR>\n" );
document.write( "y=a(x^2+3x/a+(9/4a^2)-9/4a-4<BR>\n" );
document.write( "y=a(x+3x/2a)^2-9/4a-4<BR>\n" );
document.write( "(-9/4a-4)=k=5=maximum<BR>\n" );
document.write( "-9/4a-4=5<BR>\n" );
document.write( "-9/4a=9<BR>\n" );
document.write( "-1/4a=1<BR>\n" );
document.write( "4a=-1<BR>\n" );
document.write( "a=-1/4<BR>\n" );
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