document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1107734>Question 1107734</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given that y=ax^n-23, and that y=4 when x=3 and y=220 when x=9,find the value of a and of n </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #722767 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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/cgi-bin/show-face.mpl?user=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=722767\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> for y = 4, we have<BR>\n" );
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document.write( "1) a(3^n) -23 = 4<BR>\n" );
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document.write( "for y = 220<BR>\n" );
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document.write( "2) a(9^n) -23 = 220<BR>\n" );
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document.write( "Note 3^2 = 9, then equation 2 becomes<BR>\n" );
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document.write( "3) a(3^2n) = 243<BR>\n" );
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document.write( "solve equation 1 for a<BR>\n" );
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document.write( "a = 27/(3^n)<BR>\n" );
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document.write( "substitute for a in equation 3 <BR>\n" );
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document.write( "(27/(3^n) * (3^2n) = 243<BR>\n" );
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document.write( "3^n = 243/27<BR>\n" );
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document.write( "3^n = 9<BR>\n" );
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document.write( "n = 2<BR>\n" );
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document.write( "a = 27/9 = 3<BR>\n" );
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document.write( "a = 3 and n = 2<BR>\n" );
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document.write( "check the answer<BR>\n" );
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document.write( "3(3^2) -23 = 4<BR>\n" );
document.write( "27 -23 = 4<BR>\n" );
document.write( "4 = 4<BR>\n" );
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document.write( "3(9^2) -23 = 220<BR>\n" );
document.write( "243 -23 = 220<BR>\n" );
document.write( "220 = 220<BR>\n" );
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document.write( "our answer checks<BR>\n" );
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