document.write( "Question 23716: Please solve by addition method:\r
\n" ); document.write( "\n" ); document.write( "3x - 4y = 9
\n" ); document.write( "-3x + 4y = 12 \n" ); document.write( "
Algebra.Com's Answer #12487 by rapaljer(4671)\"\" \"About 
You can put this solution on YOUR website!
If you just add these two equations together, you will subtract out the x terms AND the y terms:\r
\n" ); document.write( "\n" ); document.write( "3x - 4y = 9
\n" ); document.write( "-3x + 4y = 12\r
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\n" ); document.write( "\n" ); document.write( "0 + 0 = 21\r
\n" ); document.write( "\n" ); document.write( "Obviously this is NOT possible. There is NO way that 0 = 21! At least not in OUR lifetime!! This means that there is NO SOLUTION. Some textbooks will call this the Empty Set, and they write this either with empty set braces: { }, or with the Greek letter \"phi\" which is a 0 with a slash: \"+phi+\". I personally think this is very confusing to students, so I prefer to just call it NO SOLUTION.\r
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\n" ); document.write( "\n" ); document.write( "Now, think about what situtation could happen with equations of two straight lines that would cause a NO SOLUTION situation. What happened is that the lines are PARALLEL!!\r
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\n" ); document.write( "\n" ); document.write( "R^2 at SCC\r
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