document.write( "Question 141557: Solve using the addition principle. Dont forget to perform a check\r
\n" ); document.write( "\n" ); document.write( "-3+x=21 My answer her is -7 (I don't know if this is right) \n" ); document.write( "
Algebra.Com's Answer #103142 by Edwin McCravy(20059)\"\" \"About 
You can put this solution on YOUR website!
Solve using the addition principle. Dont forget to perform a check
\n" ); document.write( "-3+x=21 My answer her is -7 (I don't know if this is right)\r
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document.write( "No -7 is not correct.\r\n" );
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document.write( "Here's how to do it\r\n" );
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document.write( "     -3 + x = 21\r\n" );
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document.write( "                   First we get rid of the -3 on the left by adding\r\n" );
document.write( "                   +3 to both sides. We write +3 under the -3 and\r\n" );
document.write( "                   also write +3 under the 21 and draw a line:\r\n" );
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document.write( "     -3 + x = 21\r\n" );
document.write( "     +3       +3 \r\n" );
document.write( "                   \r\n" );
document.write( "                   Now we add vertically. The -3 and the +3 cancel,\r\n" );
document.write( "                   so we don't write anything under them.  Bring\r\n" );
document.write( "                   the x down. Finally, the 21 and the +3 gives 24:\r\n" );
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document.write( "     -3 + x = 21\r\n" );
document.write( "     +3       +3 \r\n" );
document.write( "          x = 24\r\n" );
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document.write( "So the solution is 24.\r\n" );
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document.write( "Now lets check by replacing x in the original by 24:\r\n" );
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document.write( "     -3 + x = 21\r\n" );
document.write( "    -3 + 24 = 21\r\n" );
document.write( "         21 = 21\r\n" );
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document.write( "Edwin
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