document.write( "Question 152235: HOW WOULD I SOLVE THIS algebracially ?\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "3/4x-2/5y=2
\n" ); document.write( "1/2x-3/5y=-2
\n" ); document.write( "

Algebra.Com's Answer #111914 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "\"%283%2F4%29x-%282%2F5%29y=2\" Start with the first equation.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"20%28%283%2Fcross%284%29%29x-%282%2Fcross%285%29%29y%29=20%282%29\" Multiply both sides by the LCD \"20\" to clear any fractions.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x-8y=40\" Distribute and multiply.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"%281%2F2%29x-%283%2F5%29y=-2\" Move onto the second equation.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"10%28%281%2Fcross%282%29%29x-%283%2Fcross%285%29%29y%29=10%28-2%29\" Multiply both sides by the LCD \"10\" to clear any fractions.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"5x-6y=-20\" Distribute and multiply.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So we have the system of equations:\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"system%2815x-8y=40%2C5x-6y=-20%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-3%285x-6y%29=-3%28-20%29\" Multiply the both sides of the second equation by -3.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-15x%2B18y=60\" Distribute and multiply.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So we have the new system of equations:\r
\n" ); document.write( "\n" ); document.write( "\"system%2815x-8y=40%2C-15x%2B18y=60%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"%2815x-8y%29%2B%28-15x%2B18y%29=%2840%29%2B%2860%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"%2815x-15x%29%2B%28-8y%2B18y%29=40%2B60\" Group like terms.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"0x%2B10y=100\" Combine like terms. Notice how the x terms cancel out.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"10y=100\" Simplify.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"y=%28100%29%2F%2810%29\" Divide both sides by \"10\" to isolate \"y\".\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"y=10\" Reduce.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "------------------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x-8y=40\" Now go back to the first equation.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x-8%2810%29=40\" Plug in \"y=10\".\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x-80=40\" Multiply.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x=40%2B80\" Add \"80\" to both sides.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"15x=120\" Combine like terms on the right side.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%28120%29%2F%2815%29\" Divide both sides by \"15\" to isolate \"x\".\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=8\" Reduce.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So our answer is \"x=8\" and \"y=10\".\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Which form the ordered pair .\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "This means that the system is consistent and independent.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice when we graph the equations, we see that they intersect at . So this visually verifies our answer.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " Graph of \"%283%2F4%29x-%282%2F5%29y=2\" (red) and \"%281%2F2%29x-%283%2F5%29y=-2\" (green) \r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );