document.write( "Question 7071: I have been working on this problem forever and can not come up with the answer in the back of my book.\r
\n" ); document.write( "\n" ); document.write( "Please help me solve the following equation : \r
\n" ); document.write( "\n" ); document.write( "│x^2 + 5│ + │x - 2│ ≤ 8 \r
\n" ); document.write( "\n" ); document.write( "This is what I did .\r
\n" ); document.write( "\n" ); document.write( "│x^2 + 5 + x - 2│≤ 8\r
\n" ); document.write( "\n" ); document.write( "-8 ≤ x^2 + 5 + x – 2 ≤ 8\r
\n" ); document.write( "\n" ); document.write( "-8 ≤ x^2 + x + 3 ≤ 8
\n" ); document.write( "then subtract -3 from all sides and get this\r
\n" ); document.write( "\n" ); document.write( "-11 ≤ x^2 + x ≤ 5, Then completing square for middle getting this\r
\n" ); document.write( "\n" ); document.write( "-11 + 1/4 ≤ x^2 + x + 1/4 ≤ 5 + 1/4\r
\n" ); document.write( "\n" ); document.write( "-43/4 ≤ x^2 + x + 1/4 ≤ 21/4\r
\n" ); document.write( "\n" ); document.write( "-43/4 ≤ (x + 1/2)^2 ≤ 21/4\r
\n" ); document.write( "\n" ); document.write( "Then don’t go any further because I now that I can not get the answer that is in the book.\r
\n" ); document.write( "\n" ); document.write( "Please tell me where I am going wrong.\r
\n" ); document.write( "\n" ); document.write( "TIA,
\n" ); document.write( "del
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Algebra.Com's Answer #3888 by khwang(438)\"\" \"About 
You can put this solution on YOUR website!
│x^2 + 5│ + │x - 2│ ≤ 8 ...(**)
\n" ); document.write( " You did wrong at very first step,because you did not apply the def. of abs
\n" ); document.write( " value correctly.\r
\n" ); document.write( "\n" ); document.write( " Note that x^2 + 5 is always positive, so |x^2 + 5| = x^2 + 5.\r
\n" ); document.write( "\n" ); document.write( " Case (i) if x - 2 >= 0, then |x-2| = x-2 ,so (**) converts to
\n" ); document.write( " x^2 + 5 + x - 2 ≤ 8
\n" ); document.write( " [Also, don't write garbages like adding -8 on both sides]
\n" ); document.write( " or x^2 + x -5 <= 0.
\n" ); document.write( " Since [-1 +/- sqrt(21)]/2 are the two roots of x^2 + x -5 = 0
\n" ); document.write( " x^2 + x -5 <= 0 implies [-1 - sqrt(21)]/2 <= x <= (-1 + sqrt(21))/2
\n" ); document.write( " (between these two roots).\r
\n" ); document.write( "\n" ); document.write( " But x >=2, and (-1 + sqrt(21))/2 < (1 + sqt(25)/2 = 2, a contradiction.
\n" ); document.write( " This means there is nosulution in this case.\r
\n" ); document.write( "\n" ); document.write( " Case (i) if x - 2 < 0, then |x-2| = -x+2 ,so (**) converts to
\n" ); document.write( " x^2 + 5 - x + 2 ≤ 8 or
\n" ); document.write( " x^2 - x -1 <= 0.
\n" ); document.write( "
\n" ); document.write( " two roots of x^2 - x -1 = 0 are [1 +/- sqrt(5)]/2
\n" ); document.write( " Hence, (-1 - sqrt(5))/2 <= x <= (-1 + sqrt(5))/2
\n" ); document.write( " Since x -2 < 0, so x < 2 and we see that (-1 + sqrt(5))/2 <2 [OK}
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\n" ); document.write( " The solution set is [(-1 - sqrt(5))/2,(-1 - sqrt(5))/2 ]
\n" ); document.write( " or (-1 - sqrt(5))/2 <= x <= (-1 + sqrt(5))/2\r
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\n" ); document.write( "\n" ); document.write( " Kenny
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