document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=118262>Question 118262</A>: <I><SPAN STYLE=\"word-break: break-all;\"> (writing linear equations in point slope form)<BR>\n" );
document.write( "write the point-slope form of an wquation of the line that passes through each pair of points.\r<BR>\n" );
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document.write( "(-1,-7),(1,3) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #86376 by </B><A HREF=/tutors/aboutme.mpl?userid=TP><B>TP(29)</B></A><img src=\"/images/stars/stars-07.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=TP><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=86376\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  m(the gradient)=vertical distance between the two points/horizontal distance between the two points.<BR>\n" );
document.write( "So m=(Y-y)/(X-x) where the two points have coordinates of (X,Y) and (x,y).<BR>\n" );
document.write( "So here (X,Y)=(-1,-7) and (x,y)=(1,3).<BR>\n" );
document.write( "Hence the gradient m=(-7-3)/(-1-1)=-10/-2=5.<BR>\n" );
document.write( "Now the general equation of a straight line is y=mx+c where m is the gradient and c is the y intercept(the y value where the line crosses the vertical Y axis).<BR>\n" );
document.write( "So far we have: y=5x+c.(i)<BR>\n" );
document.write( "We need to find the value of c.<BR>\n" );
document.write( "Since the line passes through (1,3) then we can replace x and y in our equation by 1 and 3 respectively.<BR>\n" );
document.write( "This gives (i) as: 3=5*1+c<BR>\n" );
document.write( "So 3=5+c<BR>\n" );
document.write( "Subtract 5 from each side of the equation and we get: 3-5=c<BR>\n" );
document.write( "So c=-2<BR>\n" );
document.write( "Hence the required equation is y=5x-2 ANS<BR>\n" );
document.write( "(N.B. You should verify your answer by replacing the x by -1 and the y by -7) </SPAN>\n" );
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