document.write( "Question 165304: given f(x)= \"%28x%2B1%29%28x%5E3-27%29\" find all zeros (real and imaginary) \n" ); document.write( "
Algebra.Com's Answer #121857 by jim_thompson5910(35256)\"\" \"About 
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\"f%28x%29=%28x%2B1%29%28x%5E3-27%29\" Start with the given function\r
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\n" ); document.write( "\n" ); document.write( "\"0=%28x%2B1%29%28x%5E3-27%29\" Plug in \"f%28x%29=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"0=%28x%2B1%29%28x-3%29%28x%5E2%2B3x%2B9%29\" Factor \"x%5E3-27\" to get \"%28x-3%29%28x%5E2%2B3x%2B9%29\". Note: use the difference of cubes formula.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B1=0\" or \"x-3=0\" or \"x%5E2%2B3x%2B9=0\" Set each individual factor equal to zero\r
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\n" ); document.write( "\n" ); document.write( "Solve the first two equations to get \"x=-1\" or \"x=3\". These are the first two zeros\r
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\n" ); document.write( "\n" ); document.write( "Now let's solve \"x%5E2%2B3x%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=1\", \"b=3\", 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-%283%29+%2B-+sqrt%28+%283%29%5E2-4%281%29%289%29+%29%29%2F%282%281%29%29\" Plug in \"a=1\", \"b=3\", and \"c=9\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+9-4%281%29%289%29+%29%29%2F%282%281%29%29\" Square \"3\" to get \"9\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+9-36+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%289%29\" to get \"36\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+-27+%29%29%2F%282%281%29%29\" Subtract \"36\" from \"9\" to get \"-27\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+-27+%29%29%2F%282%29\" Multiply \"2\" and \"1\" to get \"2\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+3i%2Asqrt%283%29%29%2F%282%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+=+%28-3%2B3i%2Asqrt%283%29%29%2F%282%29\" or \"x+=+%28-3-3i%2Asqrt%283%29%29%2F%282%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "So the zeros of \"x%5E2%2B3x%2B9\" are \"x+=+%28-3%2B3i%2Asqrt%283%29%29%2F%282%29\" or \"x+=+%28-3-3i%2Asqrt%283%29%29%2F%282%29\" \r
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\n" ); document.write( "\n" ); document.write( "which approximate to \"x=-1.5%2B2.598i\" or \"x=-1.5-2.598i\" \r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So in total, the 4 zeros are: \"x=-1\", \"x=3\", \"x+=+%28-3%2B3i%2Asqrt%283%29%29%2F%282%29\" or \"x+=+%28-3-3i%2Asqrt%283%29%29%2F%282%29\" \r
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\n" ); document.write( "\n" ); document.write( "Which in decimal form are \"x=-1\", \"x=3\", \"x=-1.5%2B2.598i\" or \"x=-1.5-2.598i\"
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