document.write( "Question 1199369: Solve the inequality. \r
\n" ); document.write( "\n" ); document.write( "|-4x| + |-5| ≤ 1\r
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\n" ); document.write( "\n" ); document.write( "|-4x| + -5 ≤ 1\r
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\n" ); document.write( "\n" ); document.write( "|-4x| + ≤ 1 + 5\r
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\n" ); document.write( "\n" ); document.write( "|-4x| ≤ 6\r
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\n" ); document.write( "\n" ); document.write( "-6 < -4x < 6\r
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\n" ); document.write( "\n" ); document.write( "-6/-4 > x > 6/-4\r
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\n" ); document.write( "\n" ); document.write( "3/2 > x > -3/2\r
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\n" ); document.write( "\n" ); document.write( "Let S = solution set\r
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\n" ); document.write( "\n" ); document.write( "My answer: S = {x | 3/2 > x > -3/2}\r
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\n" ); document.write( "\n" ); document.write( "Textbook answer: No solution.\r
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\n" ); document.write( "\n" ); document.write( "What did I do wrong? Why is the empty set or no solution the right answer? \r
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Algebra.Com's Answer #833227 by ikleyn(52776)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            You are wrong starting from the  FIRST  LINE  of your solution.\r
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\n" ); document.write( "\n" ); document.write( "            The correct solution is as follows.\r
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document.write( "Our starting inequality is\r\n" );
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document.write( "    |-4x| + |-5| ≤ 1.\r\n" );
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document.write( "Notice that  |-4x| = |4x|  and  |-5| = 5.  \r\n" );
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document.write( "Therefore, we can rewrite the starting inequality in this equivalent form\r\n" );
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document.write( "    |4x| + 5 <= 1\r\n" );
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document.write( "and then, subtracting 5 from both sides\r\n" );
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document.write( "    |4x| <= 1 - 5\r\n" );
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document.write( "    |4x| < -4.\r\n" );
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document.write( "But the number (absolute value) |4x| is always non-negative, so it can not be lesser than negative 4.\r\n" );
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document.write( "Hence, the original equation has no solution.\r\n" );
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document.write( "Exactly as it is stated in your textbook.\r\n" );
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