document.write( "Question 189584: Can you please help me solve this? I'm supposed to solve for all roots but I'm not sure how. \"8x%5E3%2B27=0\" \n" ); document.write( "
Algebra.Com's Answer #142259 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First, we need to factor \"8x%5E3%2B27\"\r
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\n" ); document.write( "\n" ); document.write( "\"8x%5E3%2B27\" Start with the left side of the equation.\r
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\n" ); document.write( "\n" ); document.write( "\"%282x%29%5E3%2B%283%29%5E3\" Rewrite \"8x%5E3\" as \"%282x%29%5E3\". Rewrite \"27\" as \"%283%29%5E3\".\r
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\n" ); document.write( "\n" ); document.write( "\"%282x%2B3%29%28%282x%29%5E2-%282x%29%283%29%2B%283%29%5E2%29\" Now factor by using the sum of cubes formula. Remember the sum of cubes formula is \"A%5E3%2BB%5E3=%28A%2BB%29%28A%5E2-AB%2BB%5E2%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%282x%2B3%29%284x%5E2-6x%2B9%29\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "So \"8x%5E3%2B27\" factors to \"%282x%2B3%29%284x%5E2-6x%2B9%29\".\r
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\n" ); document.write( "\n" ); document.write( "In other words, \"8x%5E3%2B27=%282x%2B3%29%284x%5E2-6x%2B9%29\"\r
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\n" ); document.write( "\n" ); document.write( "So the equation \"8x%5E3%2B27=0\" then becomes \"%282x%2B3%29%284x%5E2-6x%2B9%29=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%282x%2B3%29%284x%5E2-6x%2B9%29=0\" Start with the factored equation.\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B3=0\" or \"4x%5E2-6x%2B9=0\" Set each factor equal to zero\r
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\n" ); document.write( "\n" ); document.write( "Let's solve the first equation \"2x%2B3=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B3=0\" Start with the first equation.\r
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\n" ); document.write( "\n" ); document.write( "\"2x=-3\" Subtract 3 from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"x=-3%2F2\" Divide both sides by 2.\r
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\n" ); document.write( "\n" ); document.write( "So the first answer is \"x=-3%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's solve the second equation \"4x%5E2-6x%2B9=0\"\r
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\n" ); document.write( "\n" ); document.write( "Notice we have a quadratic equation in the form of \"ax%5E2%2Bbx%2Bc\" where \"a=4\", \"b=-6\", and \"c=9\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for x\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29\" Start with the quadratic formula\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-%28-6%29+%2B-+sqrt%28+%28-6%29%5E2-4%284%29%289%29+%29%29%2F%282%284%29%29\" Plug in \"a=4\", \"b=-6\", and \"c=9\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+sqrt%28+%28-6%29%5E2-4%284%29%289%29+%29%29%2F%282%284%29%29\" Negate \"-6\" to get \"6\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+sqrt%28+36-4%284%29%289%29+%29%29%2F%282%284%29%29\" Square \"-6\" to get \"36\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+sqrt%28+36-144+%29%29%2F%282%284%29%29\" Multiply \"4%284%29%289%29\" to get \"144\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+sqrt%28+-108+%29%29%2F%282%284%29%29\" Subtract \"144\" from \"36\" to get \"-108\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+sqrt%28+-108+%29%29%2F%288%29\" Multiply \"2\" and \"4\" to get \"8\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286+%2B-+6i%2Asqrt%283%29%29%2F%288%29\" Simplify the square root (note: If you need help with simplifying square roots, check out this solver) \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%286%2B6i%2Asqrt%283%29%29%2F%288%29\" or \"x+=+%286-6i%2Asqrt%283%29%29%2F%288%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%283%2B3i%2Asqrt%283%29%29%2F%284%29\" or \"x+=+%283-3i%2Asqrt%283%29%29%2F%284%29\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "So the other two answers are \"x+=+%283%2B3i%2Asqrt%283%29%29%2F%284%29\" or \"x+=+%283-3i%2Asqrt%283%29%29%2F%284%29\" \r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the three solutions are \"x=-3%2F2\", \"x+=+%283%2B3i%2Asqrt%283%29%29%2F%284%29\", or \"x+=+%283-3i%2Asqrt%283%29%29%2F%284%29\"
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