document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=207652>Question 207652</A>: <I><SPAN STYLE=\"word-break: break-all;\"> hello tutors. i need your help with this problem. \r<BR>\n" );
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document.write( "find an equation of the line that passes through the origin and the point (4,-8)\r<BR>\n" );
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document.write( "thank you so much, my memory is very rusty and i could really use a refresher! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #157050 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=157050\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> equation of straight line is y = mx + b where m is the slope and b is the y intercept.<BR>\n" );
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document.write( "if the line passes through the origin, then 1 point on the line is (0,0) and the other point is (4,-8) as given.<BR>\n" );
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document.write( "slope is (y2-y1)/(x2-x1)<BR>\n" );
document.write( "if we let (x1,y1) = (0,0) and we let (x2,y2) = (4,-8), then the slope equation becomes<BR>\n" );
document.write( "(-8-0)/(4-0) = (-8)/(4) = -2.<BR>\n" );
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document.write( "to solve for the y intercept we can use either point and substitute it in the equation of y = -2*x + b<BR>\n" );
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document.write( "assuming (0,0) is the point, that equation becomes 0 = -2*0 + b making b = 0<BR>\n" );
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document.write( "assuming (4,-8) is the point, that equation becomes -8 = -2*4 + b which becomes -8 = -8 * b which becomes b = 0 once we add 8 to both sides of the equation.<BR>\n" );
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document.write( "the equation of your line should be y = 2*x<BR>\n" );
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document.write( "a graph of your equation will look like this.<BR>\n" );
document.write( "when x is 0, y is 0.<BR>\n" );
document.write( "when x is 1, y is -2.<BR>\n" );
document.write( "when x is 2, y is -4.<BR>\n" );
document.write( "when x is -1, y is 2.<BR>\n" );
document.write( "when x is 2, y is 4.<BR>\n" );
document.write( "etc., as shown on the graph.<BR>\n" );
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