document.write( "Question 1186858: Consider the following polynomial. \r
\n" ); document.write( "\n" ); document.write( "F(x) = x^3 + x^2 − 22x − 40\r
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\n" ); document.write( "\n" ); document.write( "Use synthetic division to identify integer bounds of the real zeros. Find the least upper bound and the greatest lower bound guaranteed by the Upper and Lower.\r
\n" ); document.write( "\n" ); document.write( "Upper Bound:\r
\n" ); document.write( "\n" ); document.write( "Lower Bound:
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Algebra.Com's Answer #849366 by CPhill(1959)\"\" \"About 
You can put this solution on YOUR website!
Here's how to find the integer bounds using synthetic division:\r
\n" ); document.write( "\n" ); document.write( "**Understanding Upper and Lower Bound Theorem**\r
\n" ); document.write( "\n" ); document.write( "The Upper and Lower Bound Theorem helps us find integer values that are greater than or less than all real zeros of a polynomial. If we perform synthetic division with a positive number *c* and all the numbers in the bottom row are positive or zero, then *c* is an *upper bound* for the real zeros. If we perform synthetic division with a negative number *c* and the numbers in the bottom row alternate in sign (positive, negative, positive, etc., or zero), then *c* is a *lower bound* for the real zeros.\r
\n" ); document.write( "\n" ); document.write( "**Applying Synthetic Division**\r
\n" ); document.write( "\n" ); document.write( "Let's test some integer values:\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = 6:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "6 | 1 1 -22 -40
\n" ); document.write( " | 6 42 120
\n" ); document.write( " ------------------
\n" ); document.write( " 1 7 20 80
\n" ); document.write( "```\r
\n" ); document.write( "\n" ); document.write( "Since all the numbers in the bottom row are positive, 6 is an *upper bound*.\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = -5:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "-5 | 1 1 -22 -40
\n" ); document.write( " | -5 20 10
\n" ); document.write( " ------------------
\n" ); document.write( " 1 -4 -2 -30
\n" ); document.write( "```\r
\n" ); document.write( "\n" ); document.write( "The signs don't alternate.\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = -4:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "-4 | 1 1 -22 -40
\n" ); document.write( " | -4 12 40
\n" ); document.write( " ------------------
\n" ); document.write( " 1 -3 -10 0
\n" ); document.write( "```\r
\n" ); document.write( "\n" ); document.write( "-4 is a zero of the polynomial, which is acceptable.\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = -3:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "-3 | 1 1 -22 -40
\n" ); document.write( " | -3 6 48
\n" ); document.write( " ------------------
\n" ); document.write( " 1 -2 -16 8
\n" ); document.write( "```\r
\n" ); document.write( "\n" ); document.write( "The signs don't alternate.\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = -2:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "-2 | 1 1 -22 -40
\n" ); document.write( " | -2 2 40
\n" ); document.write( " ------------------
\n" ); document.write( " 1 -1 -20 0
\n" ); document.write( "```
\n" ); document.write( "-2 is also a zero of the polynomial.\r
\n" ); document.write( "\n" ); document.write( "* **Testing x = -1:**\r
\n" ); document.write( "\n" ); document.write( "```
\n" ); document.write( "-1 | 1 1 -22 -40
\n" ); document.write( " | -1 0 22
\n" ); document.write( " ------------------
\n" ); document.write( " 1 0 -22 -18
\n" ); document.write( "```
\n" ); document.write( "The signs don't alternate.\r
\n" ); document.write( "\n" ); document.write( "**Results:**\r
\n" ); document.write( "\n" ); document.write( "* **Upper Bound:** 6 (all positive or zero in bottom row)
\n" ); document.write( "* **Lower Bound:** -4 (alternating signs in bottom row, or a zero)\r
\n" ); document.write( "\n" ); document.write( "**Important Note:** The Upper and Lower Bound Theorem gives us *bounds* for the real zeros. It doesn't guarantee that the bounds themselves *are* zeros. In this case, -4 and -2 are zeros, however, that does not have to be the case.
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