document.write( "Question 199776: Hello!\r
\n" ); document.write( "\n" ); document.write( "A polynomial P is given:\r
\n" ); document.write( "\n" ); document.write( "P(x) = 2x^3 + 7x^2 + 4x - 4\r
\n" ); document.write( "\n" ); document.write( " Find all the real zeros of P\r
\n" ); document.write( "\n" ); document.write( "thanks for the homework help!
\n" ); document.write( "

Algebra.Com's Answer #150136 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First, let's find the possible rational roots.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Any rational zero can be found through this equation\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " where p and q are the factors of the last and first coefficients\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So let's list the factors of -4 (the last coefficient):\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now let's list the factors of 2 (the first coefficient):\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now let's divide each factor of the last coefficient by each factor of the first coefficient\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now simplify\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "These are all the distinct rational zeros of the function that could occur\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "-----------------------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now let's test the possible roots to see if they are actually roots.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's see if the possible zero \"1\" is really a root for the function \"2x%5E3%2B7x%5E2%2B4x-4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So let's make the synthetic division table for the function \"2x%5E3%2B7x%5E2%2B4x-4\" given the possible zero \"1\":\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "
1|274-4
| 2913
29139
\r
\n" ); document.write( "\n" ); document.write( "Since the remainder \"9\" (the right most entry in the last row) is not equal to zero, this means that \"1\" is not a zero of \"2x%5E3%2B7x%5E2%2B4x-4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's see if the possible zero \"1%2F2\" is really a root for the function \"2x%5E3%2B7x%5E2%2B4x-4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So let's make the synthetic division table for the function \"2x%5E3%2B7x%5E2%2B4x-4\" given the possible zero \"1%2F2\":\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "
1/2|274-4
| 144
2880
\r
\n" ); document.write( "\n" ); document.write( "Since the remainder \"0\" (the right most entry in the last row) is equal to zero, this means that \"1%2F2\" is a zero of \"2x%5E3%2B7x%5E2%2B4x-4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So this means that \"2x%5E3%2B7x%5E2%2B4x-4=%282x-1%29%28x%5E2%2B4x%2B4%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Note: the quotient of the division results from taking half of the first three values in the bottom row.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Note: if you didn't find a root, then you would have to keep going until either you find one or you are done with the list.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now let's solve \"x%5E2%2B4x%2B4=0\" to find the next two zeros:\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x%5E2%2B4x%2B4=0\" Start with the given equation.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice we have a quadratic in the form of \"Ax%5E2%2BBx%2BC\" where \"A=1\", \"B=4\", and \"C=4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for \"x\":\r
\n" ); document.write( "
\n" ); document.write( "
\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
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-%284%29+%2B-+sqrt%28+%284%29%5E2-4%281%29%284%29+%29%29%2F%282%281%29%29\" Plug in \"A=1\", \"B=4\", and \"C=4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B-+sqrt%28+16-4%281%29%284%29+%29%29%2F%282%281%29%29\" Square \"4\" to get \"16\". \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B-+sqrt%28+16-16+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%284%29\" to get \"16\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B-+sqrt%28+0+%29%29%2F%282%281%29%29\" Subtract \"16\" from \"16\" to get \"0\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B-+sqrt%28+0+%29%29%2F%282%29\" Multiply \"2\" and \"1\" to get \"2\". \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B-+0%29%2F%282%29\" Take the square root of \"0\" to get \"0\". \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4+%2B+0%29%2F%282%29\" or \"x+=+%28-4+-+0%29%2F%282%29\" Break up the expression. \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-4%29%2F%282%29\" or \"x+=++%28-4%29%2F%282%29\" Combine like terms. \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+-2\" or \"x+=+-2\" Simplify. \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the two solutions are \"x+=+-2\" or \"x+=+-2\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "We can simply write this as \"x=-2\" with a multiplicity of 2\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "===========================================================================\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Answer:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the three zeros of \"P%28x%29+=+2x%5E3+%2B+7x%5E2+%2B+4x+-+4\" are: \"x=1%2F2\" and \"x+=+-2\" (with a multiplicity of 2)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "If you have any questions, email me at jim_thompson5910@hotmail.com\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );