document.write( "Question 184999This question is from textbook
\n" ); document.write( ": I am given to sets of points (-2,-4) and (2,1). I need to write an equation.
\n" ); document.write( "this is what I did:\r
\n" ); document.write( "\n" ); document.write( "m= 1- (-4)/2- (-2) = 3/0 = 3
\n" ); document.write( "y= 3x + b
\n" ); document.write( "-4 = 3(-2) + b
\n" ); document.write( "-4 = -6 + b
\n" ); document.write( "+6 +6\r
\n" ); document.write( "\n" ); document.write( "-2=b ???????
\n" ); document.write( "Very Confusing
\n" ); document.write( "

Algebra.Com's Answer #138819 by Earlsdon(6294)\"\" \"About 
You can put this solution on YOUR website!
Start with the general linear equation in the \"slope-intercept\" form:
\n" ); document.write( "\"y+=+mx%2Bb\"
\n" ); document.write( "Find the slope from the given points (-2,-4) (2,1) using:
\n" ); document.write( "\"m+=+%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\" and the (\"x%5B1%5D\",\"y%5B1%5D\") are the x- and y-coordinates of the first point. Similarly for the second point, so...
\n" ); document.write( "\"m+=+%281-%28-4%29%29%2F%282-%28-2%29%29\"
\n" ); document.write( "\"m+=+5%2F4\" Now plug this into the general equation we had at the start.
\n" ); document.write( "\"y+=+%285%2F4%29x%2Bb\" Now we need to find the value of b, the y-intercept. This is done by substituting the x- and y-coordinates of either one of the two given points. Let's use the second point (2,1).
\n" ); document.write( "\"y+=+%285%2F4%29x%2Bb\" Substitute x = 2 and y = 1 and solve for b.
\n" ); document.write( "\"1+=+%285%2F4%29%282%29%2Bb\"
\n" ); document.write( "\"1+=+5%2F2+%2B+b\" Subtract \"5%2F2\" from both sides of the equation.
\n" ); document.write( "\"%282%2F2%29-%285%2F2%29+=+b\" Simplify.
\n" ); document.write( "\"b+=+-3%2F2\" Now you can write the final equation in slope-intercept form:
\n" ); document.write( "\"highlight%28y+=+%285%2F4%29x-3%2F2%29\"
\n" ); document.write( "A few comments on your work.
\n" ); document.write( "It seems that you are having trouble handling the addition/subtraction of positive/negative integers.
\n" ); document.write( "Remember...to subtract an integer, you add its additive inverse (opposite), thus:
\n" ); document.write( "\"1-%28-4%29+=+1%2B%284%29\"=\"5\" and
\n" ); document.write( "\"2-%28-2%29+=+2%2B2\"=\"4\"
\n" ); document.write( "Furthermore, you came up wth a slope \"m+=+3%2F0\" but remember, if a fraction has a zero in the denominator, it considered \"undefined\" because division by zero is not defined in mathematics.
\n" ); document.write( "
\n" );