document.write( "Question 196635: Hi!\r
\n" ); document.write( "\n" ); document.write( "On the following problem I keep getting the incorrect answer. I think I'm close to the right answer just making a small error somewhere. Can you help me?\r
\n" ); document.write( "\n" ); document.write( "Solve the equation for the variable x. The constant a represents a positive real number. \r
\n" ); document.write( "\n" ); document.write( "a^3x^3 + 64 = 0
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Algebra.Com's Answer #147376 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"a%5E3x%5E3+%2B+64+=+0\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"%28ax%29%5E3+%2B+64+=+0\" Rewrite \"a%5E3x%5E3\" as \"%28ax%29%5E3\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28ax%29%5E3+%2B+4%5E3+=+0\" Rewrite \"64\" as \"%284%29%5E3\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28ax%2B4%29%28%28ax%29%5E2-%28ax%29%284%29%2B%284%29%5E2%29+=+0\" Factor the left side using the sum of cubes formula\r
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\n" ); document.write( "\n" ); document.write( "Recall, 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( "\"%28ax%2B4%29%28a%5E2x%5E2-4ax%2B16%29+=+0\" Multiply and simplify\r
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\n" ); document.write( "\n" ); document.write( "\"ax%2B4=0\" or \"a%5E2x%5E2-4ax%2B16=0\" Use the zero product property to break up the factors\r
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\n" ); document.write( "\n" ); document.write( "Let's solve the first equation: \"ax%2B4=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"ax%2B4=0\" Start with the first equation.\r
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\n" ); document.write( "\n" ); document.write( "\"ax=-4\" Subtract 4 from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"x=-4%2Fa\" Divide both sides by \"a\" to isolate \"x\".\r
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\n" ); document.write( "\n" ); document.write( "So the first solution is \"x=-4%2Fa\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's solve the second equation: \"a%5E2x%5E2-4ax%2B16=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"a%5E2x%5E2-4ax%2B16=0\" Start with the second equation.\r
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\n" ); document.write( "\n" ); document.write( "Notice we have a quadratic in the form of \"Ax%5E2%2BBx%2BC\" where \"A=a%5E2\", \"B=-4a\", and \"C=16\"\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( " Plug in \"A=a%5E2\", \"B=-4a\", and \"C=16\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+sqrt%28+%28-4a%29%5E2-4%28a%5E2%29%2816%29+%29%29%2F%282%28a%5E2%29%29\" Negate -4a to get 4a\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+sqrt%28+16a%5E2-4%28a%5E2%29%2816%29+%29%29%2F%282%28a%5E2%29%29\" Square -4a to get \"16a%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+sqrt%28+16a%5E2-64a%5E2+%29%29%2F%282a%5E2%29\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+sqrt%28+-48a%5E2+%29%29%2F%282a%5E2%29\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+sqrt%28+-1%2A16%2A3%2Aa%5E2+%29%29%2F%282a%5E2%29\" Factor -48 into \"-1%2A16%2A3\"\r
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\n" ); document.write( "\n" ); document.write( " Break up the square root.\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+i%2A4%2Asqrt%283%29%2Aa+%29%2F%282a%5E2%29\" Simplify the square roots and replace \"sqrt%28-1%29\" with \"i\".\r
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\n" ); document.write( "\n" ); document.write( "Note: \"i=sqrt%28-1%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B-+4a%2Asqrt%283%29%2Ai+%29%2F%282a%5E2%29\" Rearrange the terms.\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284a+%2B+4a%2Asqrt%283%29%2Ai+%29%2F%282a%5E2%29\" or \"a+=+%284a+-+4a%2Asqrt%283%29%2Ai+%29%2F%282a%5E2%29\" Break up the \"plus/minus\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%282+%2B+2%2Asqrt%283%29%2Ai+%29%2Fa\" or \"x+=+%282+-+2%2Asqrt%283%29%2Ai+%29%2Fa\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "So the next two solutions are \"x+=+%282+%2B+2%2Asqrt%283%29%2Ai+%29%2Fa\" or \"x+=+%282+-+2%2Asqrt%283%29%2Ai+%29%2Fa\"\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=-4%2Fa\", \"x+=+%282+%2B+2%2Asqrt%283%29%2Ai+%29%2Fa\" or \"x+=+%282+-+2%2Asqrt%283%29%2Ai+%29%2Fa\"
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