document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=995660>Question 995660</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If f(2x+1)=2x^2 -1 and g(x)= 3+ x then (g o f)(7) is?? The answer is 20 but i need to know how yo do it thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #614425 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=614425\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> i think i figured it out.\r<BR>\n" );
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document.write( "first time for everything and this is the first time i saw one like this.\r<BR>\n" );
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document.write( "but i got 20 so i must be doing something right.\r<BR>\n" );
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document.write( "i think.\r<BR>\n" );
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document.write( "you have 2 functions.\r<BR>\n" );
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document.write( "f(2x+1) = 2x^2 - 1\r<BR>\n" );
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document.write( "g(x) = 3 + x\r<BR>\n" );
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document.write( "you want to find the value of gof(7).\r<BR>\n" );
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document.write( "gof(x) is equal to g(f(x)).\r<BR>\n" );
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document.write( "so was start with f(x).\r<BR>\n" );
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document.write( "but it's not f(x), it's f(2x+1)\r<BR>\n" );
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document.write( "in order to make that f(7), we have to find a value of x that makes 2x+1 = 7\r<BR>\n" );
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document.write( "that value of x = 3.\r<BR>\n" );
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document.write( "you have to replace x with 3 in the function.\r<BR>\n" );
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document.write( "f(3) = 2x^2 - 1 becomes f(3) = 18 - 1 = 17\r<BR>\n" );
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document.write( "you have f(3) = 17.\r<BR>\n" );
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document.write( "now you want to take g(x) = 3 + x and replace x with 17.\r<BR>\n" );
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document.write( "you will get g(17) = 3 + 17 which then becomes 20.\r<BR>\n" );
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document.write( "scary problem, but the whole idea appeared to be that, in order to get f(7), you needed to find the value of x that made 2x+1 = 7.\r<BR>\n" );
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document.write( "that value of x was 3).\r<BR>\n" );
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document.write( "so f(7) means you have to replace 2x+1 with 7 and that only happens when x = 3.\r<BR>\n" );
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document.write( "so f(2x+1) = 2x^2 - 1 becomes f(3) when 2x+1 = 7.\r<BR>\n" );
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document.write( "like i said, i never saw one like this before, but i got the right answer so i'm reasonably satisfied i interpreted it correctly.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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