document.write( "Question 74625: One sister is older than the other by 5 years. The product of their ages is twice the age of their mother who is 33. What is the age of the older sister? \r
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Algebra.Com's Answer #53598 by Edwin McCravy(20054)\"\" \"About 
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document.write( "One sister is older than the other by 5 years.\r\n" );
document.write( "The product of their ages is twice the age of \r\n" );
document.write( "their mother who is 33. What is the age of \r\n" );
document.write( "the older sister? \r\n" );
document.write( "Setup the equation\r\n" );
document.write( "solve the equation\r\n" );
document.write( "write the answer\r\n" );
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document.write( "Let the younger sister's age be x\r\n" );
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document.write( ">>...One sister is older than the other by \r\n" );
document.write( "     5 years...<<\r\n" );
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document.write( "Translation:  The older siste's age is x + 5\r\n" );
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document.write( ">>...The product of their ages is twice the \r\n" );
document.write( "     age of their mother who is 33...<<\r\n" );
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document.write( "Erase the unnecessary words \"the age of their \r\n" );
document.write( "mother who is\". So it now reads\r\n" );
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document.write( ">>...The product of their ages is twice...33...<<\r\n" );
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document.write( "Replace \"twice...33\"\" by 66\r\n" );
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document.write( ">>...The product of their ages is 66<< \r\n" );
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document.write( "Replace the words \"the product of their ages\" by \r\n" );
document.write( "     \"x(x + 5)\". So now it reads:\r\n" );
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document.write( ">>...x(x + 5) is 66...<<\r\n" );
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document.write( "Replace the word \"is\" by \" = \".  That gives \r\n" );
document.write( "us our equation:\r\n" );
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document.write( "              x(x + 5) = 66\r\n" );
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document.write( "Remove the parentheses:\r\n" );
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document.write( "               x² + 5x = 66\r\n" );
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document.write( "Get 0 on the right side\r\n" );
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document.write( "          x² + 5x - 66 = 0\r\n" );
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document.write( "Factor the left side:\r\n" );
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document.write( "       (x + 11)(x - 6) = 0\r\n" );
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document.write( "Set each factor = 0\r\n" );
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document.write( "     x + 11 = 0 gives x = -11\r\n" );
document.write( "      x - 6 = 0 gives x = 6\r\n" );
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document.write( "Discard the negative answer.\r\n" );
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document.write( "So the younger sister's age is x = 6 \r\n" );
document.write( "    years.\r\n" );
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document.write( "The older sister's age is x + 5 \r\n" );
document.write( "    which is 6 + 5 = 11 years.\r\n" );
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document.write( "Edwin
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