document.write( "Question 389617: my math homework said to define identity in equations but i have no clue what that means plz help me \n" ); document.write( "
Algebra.Com's Answer #276150 by Edwin McCravy(20055)\"\" \"About 
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document.write( "There are three basic kinds of sequations:\r\n" );
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document.write( "1. Conditional equations\r\n" );
document.write( "2. Identity equations\r\n" );
document.write( "3. Contradiction equations\r\n" );
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document.write( "Conditional equations are true for some values of the variable, say x,\r\n" );
document.write( "and false for others.\r\n" );
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document.write( "2x + 1 = 7  is true when 3 is substituted for x\r\n" );
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document.write( "2(3) + 1 = 7\r\n" );
document.write( "   6 + 1 = 7\r\n" );
document.write( "       7 = 7\r\n" );
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document.write( "However\r\n" );
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document.write( "2x + 1 = 7  is false when 4 is substituted for x\r\n" );
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document.write( "2(4) + 1 = 7\r\n" );
document.write( "   8 + 1 = 7\r\n" );
document.write( "       9 = 7\r\n" );
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document.write( "and that's false.\r\n" );
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document.write( "An identity is an equation in a variable, say x, such that every value\r\n" );
document.write( "of x makes it true.\r\n" );
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document.write( "Here is a simple identity\r\n" );
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document.write( "x + x = 2x\r\n" );
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document.write( "Any value you sustitute for x will make it true.\r\n" );
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document.write( "If you substitute x = 17 it is true\r\n" );
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document.write( "17 + 17 = 2(17)\r\n" );
document.write( "     34 = 34\r\n" );
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document.write( "If you substitute x = 1 it is true:\r\n" );
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document.write( "1 + 1 = 2(1)\r\n" );
document.write( "    2 = 2\r\n" );
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document.write( "If you substitute -31.791 it is true:\r\n" );
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document.write( "-31.791 + (-31.791) = 2(-31.791)\r\n" );
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document.write( "            -63.582 = -63.582\r\n" );
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document.write( "Here's a more complicated identity:\r\n" );
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document.write( "(x-1)² + 3x² + 8 = (2x-3)² + 10x\r\n" );
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document.write( "Substitute random numbers for x.  You'll see that\r\n" );
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document.write( "it is always true\r\n" );
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document.write( "-------------------------------------\r\n" );
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document.write( "Equations that are never true are called \"contradiction equations\":\r\n" );
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document.write( "Here;'s a contradiction equation:\r\n" );
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document.write( "3x = x + 2x + 7\r\n" );
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document.write( "Edwin
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