document.write( "Question 672948: Solve using Substitution: \r
\n" ); document.write( "\n" ); document.write( "8x-6y=4
\n" ); document.write( "2x-y=-2\r
\n" ); document.write( "\n" ); document.write( "I did what I could and found x to be 2, but I can't find the y value. thanks! \n" ); document.write( "
Algebra.Com's Answer #418422 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
\r\n" );
document.write( "\r\n" );
document.write( "Sorry, that's wrong. Do it this way:\r\n" );
document.write( "\r\n" );
document.write( " First equation:   8x - 6y =  4\r\n" );
document.write( "Second equation:   2x -  y = -2\r\n" );
document.write( "\r\n" );
document.write( "Solve the second equation for y, that's because y in the\r\n" );
document.write( "second equation has a coefficient of -1 and that makes \r\n" );
document.write( "it solvable without fractions:\r\n" );
document.write( "\r\n" );
document.write( "Second equation:   2x -  y = -2\r\n" );
document.write( "                        -y = -2 - 2x\r\n" );
document.write( "\r\n" );
document.write( "Consider the coefficient of y to be -1\r\n" );
document.write( "\r\n" );
document.write( "                       -1y = -2 - 2x\r\n" );
document.write( "\r\n" );
document.write( "Then divide through by -1\r\n" );
document.write( "\r\n" );
document.write( "                       \"%28-1y%29%2F%28-1%29\" = \"%28-2%29%2F%28-1%29\" - \"%282x%29%2F%28-1%29\"\r\n" );
document.write( "\r\n" );
document.write( "                         y = 2 + 2x\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Since y and 2 + 2x are equal you can sustitute (2 + 2x) in place of y in\r\n" );
document.write( "the first equation:\r\n" );
document.write( "\r\n" );
document.write( " First equation:   8x - 6y = 4\r\n" );
document.write( "                   8x - 6(2 + 2x) = 4\r\n" );
document.write( "Solve that for x:  \r\n" );
document.write( "                    8x - 12 - 12x = 4 \r\n" );
document.write( "                         -4x - 12 = 4\r\n" );
document.write( "                              -4x = 16\r\n" );
document.write( "                                x = \"16%2F%28-4%29\"\r\n" );
document.write( "                                x = -4\r\n" );
document.write( "\r\n" );
document.write( "Go back to where you solved for y\r\n" );
document.write( "\r\n" );
document.write( "                                y = 2 + 2x\r\n" );
document.write( "\r\n" );
document.write( "and since x and -4 are equal you can substitute (-4) for x\r\n" );
document.write( "and find y:\r\n" );
document.write( "\r\n" );
document.write( "                               y = 2 + 2x\r\n" );
document.write( "                               y = 2 + 2(-4)\r\n" );
document.write( "                               y = 2 - 8\r\n" );
document.write( "                               y = -6\r\n" );
document.write( "\r\n" );
document.write( "So the solution is x = -4, y = -6, often written as (x,y) = (-4,-6)\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" ); document.write( "
\n" );