document.write( "Question 10848: Solve the following equation in the complex number system\r
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\n" ); document.write( "\n" ); document.write( "1.X^3 - 8 = 0
\n" ); document.write( "2. X^3 + 27 = 0\r
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\n" ); document.write( "\n" ); document.write( "my solution
\n" ); document.write( "1. X^3 - 8 = 0
\n" ); document.write( " X^3 = 8
\n" ); document.write( " X= 3root 8
\n" ); document.write( " X= +- 2
\n" ); document.write( " X= +2 , -2\r
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\n" ); document.write( "\n" ); document.write( "2. X^3 + 27 = 0
\n" ); document.write( " x^3=27
\n" ); document.write( " X =+- 3root 27
\n" ); document.write( " X= + - 3
\n" ); document.write( " X= =3, -3\r
\n" ); document.write( "\n" ); document.write( "I know I'm wrong but I don't know why. kindly help.
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Algebra.Com's Answer #5811 by Earlsdon(6294)\"\" \"About 
You can put this solution on YOUR website!
1) \"x%5E3+-+8+=+0+\" Add 8 to both sides, which you did already.\r
\n" ); document.write( "\n" ); document.write( "\"x%5E3+=+8\" Take the cube root of both sides.\r
\n" ); document.write( "\n" ); document.write( "\"x+=+2\" \r
\n" ); document.write( "\n" ); document.write( " -2 is not a root since: \"+%28-2%29%5E3+=+%28-2%29%28-2%29%28-2%29\" = -8\r
\n" ); document.write( "\n" ); document.write( "2) \"x%5E3+%2B+27+=+0\" Subtract 27 from both sides.\r
\n" ); document.write( "\n" ); document.write( "\"x%5E3+=+-27\" Take the cube root of both sides.\r
\n" ); document.write( "\n" ); document.write( "\"x+=+-3\" \r
\n" ); document.write( "\n" ); document.write( "+3 is not a root since: \"%28%2B3%29%5E3+=+%28%2B3%29%28%2B3%29%28%2B3%29\" = +27\r
\n" ); document.write( "\n" ); document.write( "Please ignore the above...it's wrong!\r
\n" ); document.write( "\n" ); document.write( "1) \"x%5E3+-+8+=+0\" This is the difference of two cubes which can be factored as follows:\r
\n" ); document.write( "\n" ); document.write( "\"%28x+-+2%29%28x%5E2+%2B+2x+%2B+4%29+=+0\"\r
\n" ); document.write( "\n" ); document.write( "\"x+-+2+=+0\", so \"x+=+2\" One root.\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+%2B+2x++%2B+4+=+0\" Use the quadratic formula: \"x+=+%28-b%2B-sqrt%28b%5E2+-+4ac%29%29%2F2a\"\r
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2%2B-sqrt%284-16%29%29%2F2\"\r
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2%2B-sqrt%28-12%29%29%2F2\"\r
\n" ); document.write( "\n" ); document.write( "\"x+=+-1%2B-sqrt%28-3%2A4%29%2F2\"\r
\n" ); document.write( "\n" ); document.write( "\"x+=+-1%2Bsqrt%283%29i\" or \"x+=+-1-sqrt%283%29i\" The other two roots.\r
\n" ); document.write( "\n" ); document.write( "2) \"x%5E3+%2B+27+=+0\" This is the sum of two cubes which can be factored as follows:\r
\n" ); document.write( "\n" ); document.write( "\"%28x+%2B+3%29%28x%5E2+-+3x+%2B+9%29+=+0\" Setting each factor = 0.
\n" ); document.write( "\"%28x+%2B+3%29+=+0\"
\n" ); document.write( "\"x+=+-3\" This is one of the roots.\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+-+3x+%2B+9+=+0\" Use the quadratic formula: \"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a\"\r
\n" ); document.write( "\n" ); document.write( "\"x=%283%2B-sqrt%289-36%29%29%2F2\"
\n" ); document.write( "\"x=%283%2F2%29%2B-sqrt%28-27%29%2F2\"
\n" ); document.write( "\"x=%283%2F2%29%2B3sqrt%283%29i%2F2\" or \"x=%283%2F2%29-3sqrt%283%29i%2F2\" The other two roots.\r
\n" ); document.write( "\n" ); document.write( "These can also be written:\r
\n" ); document.write( "\n" ); document.write( "\"x+=+%283%2F2%29%281%2Bsqrt%283%29i%29\" and
\n" ); document.write( "\"x+=+%283%2F2%29%281-sqrt%283%29i%29\"\r
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