document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=117996>Question 117996</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the equation of the line that goes through the given point and has the given slope. Write the answer in slope-intrecept form.\r<BR>\n" );
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document.write( "(-1,-5),-8\r<BR>\n" );
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document.write( "this is what I did <BR>\n" );
document.write( "-5y=-8x + -1  I got b= -13  which is incorrect </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #86035 by </B><A HREF=/tutors/aboutme.mpl?userid=bucky><B>bucky(2189)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=bucky><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=86035\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The slope intercept form of an equation is:<BR>\n" );
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document.write( "y = mx + b<BR>\n" );
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document.write( "where m is the slope and b is the point on the y-axis at which the line crosses the y-axis.<BR>\n" );
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document.write( "In this problem you are told that the line is to have a slope of -8. So you substitute<BR>\n" );
document.write( "-8 for m in the slope intercept form and you get:<BR>\n" );
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document.write( "y = -8x + b<BR>\n" );
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document.write( "You are also told that the point (-1, -5) must be on the line.  This means that the equation<BR>\n" );
document.write( "must be true when x equals -1 and y equals -5. So in the slope intercept form you replace x by <BR>\n" );
document.write( "-1 and y by -5 to get:<BR>\n" );
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document.write( "-5 = -8(-1) + b<BR>\n" );
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document.write( "Do the multiplication on the right side and this equation becomes:<BR>\n" );
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document.write( "-5 = 8 + b<BR>\n" );
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document.write( "Get rid of the 8 on the right side by subtracting 8 from both sides and you are left with:<BR>\n" );
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document.write( "-13 = b<BR>\n" );
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document.write( "This value for b is then substituted into the slope intercept equation that was written above:<BR>\n" );
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document.write( "y = -8x + b<BR>\n" );
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document.write( "and when you replace b by -13 the equation becomes:<BR>\n" );
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document.write( "y = -8x - 13<BR>\n" );
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document.write( "By inspection you can see that the slope of this line (the multiplier of x) is -8 and the<BR>\n" );
document.write( "line crosses the y-axis at y = -13.<BR>\n" );
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document.write( "As a check, in this equation replace x by -1 to get:<BR>\n" );
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document.write( "y = -8(-1) - 13<BR>\n" );
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document.write( "Do the multiplication on the right side and it becomes:<BR>\n" );
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document.write( "y = +8 - 13<BR>\n" );
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document.write( "Add the two numbers on the right side and you get:<BR>\n" );
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document.write( "y = -5<BR>\n" );
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document.write( "So when x equals -1 the corresponding value of y is -5. This tells you that the point (-1, -5)<BR>\n" );
document.write( "is on the graph. So the answer is correct. The answer is:<BR>\n" );
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document.write( "y = -8x - 13<BR>\n" );
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document.write( "Hope this problem helps you understand the slope intercept form a little better.<BR>\n" );
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