document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=620692>Question 620692</A>: <I><SPAN STYLE=\"word-break: break-all;\"> type the correct equation if you are given this coordinates (0,1) (2,-3) (4,-7) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #390347 by </B><A HREF=/tutors/aboutme.mpl?userid=math-vortex><B>math-vortex(648)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=math-vortex><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=math-vortex><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=390347\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi, there--<BR>\n" );
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document.write( "When you are given a series of ordered pairs (x,y) and you want an equation, it sometimes helps to write the x and y values in a table and look for the rate of change (slope).<BR>\n" );
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document.write( " x  y<BR>\n" );
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document.write( "0   1<BR>\n" );
document.write( "2 -3<BR>\n" );
document.write( "4 -7<BR>\n" );
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document.write( "Notice that the x-terms increase by 2 each time, and the y-terms decrease by 4 each time.<BR>\n" );
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document.write( "The rate of change is defined as the \"change in y divided by the change in x. Thus the rate of change, or slope, is -4/2=-2.<BR>\n" );
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document.write( "Since the rate of change is constant, we know that we will have the equation for a line. Since we no have the slope and some points on the line, the point-slope form is a good method to use.<BR>\n" );
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document.write( "Next, notice that the point (0,1) is the y-intercept for the equation, the point where the line crosses the y-axis.<BR>\n" );
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document.write( "We can use the slope-intercept form (y=mx+b) to write an equation for the line. THe slope is m and the y-term of the y-intercept is b.<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=mx%2Bb ALIGN=MIDDLE  ALT=\"y=mx%2Bb\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=-2x%2B1 ALIGN=MIDDLE  ALT=\"y=-2x%2B1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "You can double check your work by making sure that all three points are on this line. Substitute the points for x and y in the equation.<BR>\n" );
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document.write( "(0,1)<BR>\n" );
document.write( "y=-2x+1<BR>\n" );
document.write( "1=-2(0)+1<BR>\n" );
document.write( "1=1<BR>\n" );
document.write( "Check!<BR>\n" );
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document.write( "(2,-3)<BR>\n" );
document.write( "y=-2x+1<BR>\n" );
document.write( "-3=-2(2)+1<BR>\n" );
document.write( "-3=-4+1<BR>\n" );
document.write( "-3=-3<BR>\n" );
document.write( "Check!!<BR>\n" );
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document.write( "(4,-7)<BR>\n" );
document.write( "y=-2x+1<BR>\n" );
document.write( "-7=-2(4)+1<BR>\n" );
document.write( "-7=-8+1<BR>\n" );
document.write( "-7=-7<BR>\n" );
document.write( "Check!!!<BR>\n" );
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document.write( "Hope this helps! Feel free to email if you still have questions.<BR>\n" );
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document.write( "Ms.Figgy<BR>\n" );
document.write( "math.in.the.vortex@gmail.com<BR>\n" );
document.write( " </SPAN>\n" );
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