document.write( "Question 195821: What are the factors of n^2-7n+10 \n" ); document.write( "

Algebra.Com's Answer #146840 by jim_thompson5910(35256) $\"\"$ $\"About$

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\n" ); document.write( "\n" ); document.write( "Looking at the expression $\"n%5E2-7n%2B10\"$ , we can see that the first coefficient is $\"1\"$ , the second coefficient is $\"-7\"$ , and the last term is $\"10\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient $\"1\"$ by the last term $\"10\"$ to get $\"%281%29%2810%29=10\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Now the question is: what two whole numbers multiply to $\"10\"$ (the previous product) and add to the second coefficient $\"-7\"$ ?\r
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\n" ); document.write( "\n" ); document.write( "To find these two numbers, we need to list all of the factors of $\"10\"$ (the previous product).\r
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\n" ); document.write( "\n" ); document.write( "Factors of $\"10\"$ :\r
\n" ); document.write( "\n" ); document.write( "1,2,5,10\r
\n" ); document.write( "\n" ); document.write( "-1,-2,-5,-10\r
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\n" ); document.write( "\n" ); document.write( "Note: list the negative of each factor. This will allow us to find all possible combinations.\r
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\n" ); document.write( "\n" ); document.write( "These factors pair up and multiply to $\"10\"$ .\r
\n" ); document.write( "\n" ); document.write( "1*10
\n" ); document.write( "2*5
\n" ); document.write( "(-1)*(-10)
\n" ); document.write( "(-2)*(-5)\r
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\n" ); document.write( "\n" ); document.write( "Now let's add up each pair of factors to see if one pair adds to the middle coefficient $\"-7\"$ :\r
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First Number	Second Number	Sum
1	10	1+10=11
2	5	2+5=7
-1	-10	-1+(-10)=-11
-2	-5	-2+(-5)=-7

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\n" ); document.write( "\n" ); document.write( "From the table, we can see that the two numbers $\"-2\"$ and $\"-5\"$ add to $\"-7\"$ (the middle coefficient).\r
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\n" ); document.write( "\n" ); document.write( "So the two numbers $\"-2\"$ and $\"-5\"$ both multiply to $\"10\"$ and add to $\"-7\"$ \r
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\n" ); document.write( "\n" ); document.write( "Now replace the middle term $\"-7n\"$ with $\"-2n-5n\"$ . Remember, $\"-2\"$ and $\"-5\"$ add to $\"-7\"$ . So this shows us that $\"-2n-5n=-7n\"$ .\r
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\n" ); document.write( "\n" ); document.write( " $\"n%5E2%2Bhighlight%28-2n-5n%29%2B10\"$ Replace the second term $\"-7n\"$ with $\"-2n-5n\"$ .\r
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\n" ); document.write( "\n" ); document.write( " $\"%28n%5E2-2n%29%2B%28-5n%2B10%29\"$ Group the terms into two pairs.\r
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\n" ); document.write( "\n" ); document.write( " $\"n%28n-2%29%2B%28-5n%2B10%29\"$ Factor out the GCF $\"n\"$ from the first group.\r
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\n" ); document.write( "\n" ); document.write( " $\"n%28n-2%29-5%28n-2%29\"$ Factor out $\"5\"$ from the second group. The goal of this step is to make the terms in the second parenthesis equal to the terms in the first parenthesis.\r
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\n" ); document.write( "\n" ); document.write( " $\"%28n-5%29%28n-2%29\"$ Combine like terms. Or factor out the common term $\"n-2\"$ \r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So $\"n%5E2-7n%2B10\"$ factors to $\"%28n-5%29%28n-2%29\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Note: you can check the answer by FOILing $\"%28n-5%29%28n-2%29\"$ to get $\"n%5E2-7n%2B10\"$ or by graphing the original expression and the answer (the two graphs should be identical).
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