document.write( "Question 88390: Hello I am currently trying to figure out this problem. \r
\n" ); document.write( "\n" ); document.write( "Find all real and imaginary zeros for each polynomial function\r
\n" ); document.write( "\n" ); document.write( "f(x)=x^3-27\r
\n" ); document.write( "\n" ); document.write( "This is how I started working out the problem, I have no examples to really work with on this style of problem so I am not to sure if I have even started it correctly.\r
\n" ); document.write( "\n" ); document.write( "f(x)=x^3-27
\n" ); document.write( "x^3-27=0
\n" ); document.write( " +27=+27
\n" ); document.write( "x^3=27\r
\n" ); document.write( "\n" ); document.write( "I am stuck and not sure where to go next. Your help at solving this problem will be greatly appreciated.\r
\n" ); document.write( "\n" ); document.write( "Thank you
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Algebra.Com's Answer #64189 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"x%5E3-27=0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28x-3%29%28x%5E2%2B3x%2B9%29=0\" Factor using the difference of cubes \r
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\n" ); document.write( "\n" ); document.write( "\"x-3=0\" Set the first factor equal to zero\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\" Add 3 to both sides\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2%2B3x%2B9=0\" Set the second factor equal to zero\r
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\n" ); document.write( "\n" ); document.write( "Now let's use the quadratic formula to solve for x:\r
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\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"ax%5E2%2Bbx%2Bc=0\"\r
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\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"\r
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\n" ); document.write( "\n" ); document.write( "So lets solve \"x%5E2%2B3%2Ax%2B9=0\" (notice \"a=1\", \"b=3\", and \"c=9\")\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+%283%29%5E2-4%2A1%2A9+%29%29%2F%282%2A1%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%2A1%2A9+%29%29%2F%282%2A1%29\" Square 3 to get 9\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+sqrt%28+9%2B-36+%29%29%2F%282%2A1%29\" Multiply \"-4%2A9%2A1\" 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%2A1%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+3%2Ai%2Asqrt%283%29%29%2F%282%2A1%29\" Simplify the square root (note: since we cannot take the square root of a negative value, we must factor out \"i=sqrt%28-1%29\" to make the radicand positive)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-3+%2B-+3%2Ai%2Asqrt%283%29%29%2F%282%29\" Multiply 2 and 1 to get 2\r
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\n" ); document.write( "\n" ); document.write( "After simplifying, the quadratic has roots of\r
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\n" ); document.write( "\n" ); document.write( "\"x=-1.5+%2B+2.59807621135332i\" or \"x=-1.5+-+2.59807621135332i\"\r
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\n" ); document.write( "\n" ); document.write( "So the polynomial has one real zero:\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\"\r
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\n" ); document.write( "\n" ); document.write( "and 2 imaginary zeros\r
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\n" ); document.write( "\n" ); document.write( "\"x=-1.5+%2B+2.59807621135332i\" or \"x=-1.5+-+2.59807621135332i\"\r
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\n" ); document.write( "\n" ); document.write( "Notice if we graph the polynomial \"y=x%5E3-27\", we get\r
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\n" ); document.write( "\n" ); document.write( "\"+graph%28+900%2C+900%2C+-35%2C+10%2C+-35%2C+10%2C+x%5E3-27%29+\" graph of \"y=x%5E3-27\"\r
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\n" ); document.write( "\n" ); document.write( "and we can see that the polynomial has one x-intercept (which is \"x=3\"). Since this polynomial has at most 3 complex roots, there must be 2 imaginary roots (because one is real). So our answer is verified.
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