document.write( "Question 388541: Factor 4x^2-28x+48 pleaseeeeee \n" ); document.write( "

Algebra.Com's Answer #274885 by jim_thompson5910(35256) $\"\"$ $\"About$

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\n" ); document.write( "\n" ); document.write( " $\"4x%5E2-28x%2B48\"$ Start with the given expression.\r
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\n" ); document.write( "\n" ); document.write( " $\"4%28x%5E2-7x%2B12%29\"$ Factor out the GCF $\"4\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Now let's try to factor the inner expression $\"x%5E2-7x%2B12\"$ \r
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\n" ); document.write( "\n" ); document.write( "Looking at the expression $\"x%5E2-7x%2B12\"$ , we can see that the first coefficient is $\"1\"$ , the second coefficient is $\"-7\"$ , and the last term is $\"12\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient $\"1\"$ by the last term $\"12\"$ to get $\"%281%29%2812%29=12\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Now the question is: what two whole numbers multiply to $\"12\"$ (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 $\"12\"$ (the previous product).\r
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\n" ); document.write( "\n" ); document.write( "Factors of $\"12\"$ :\r
\n" ); document.write( "\n" ); document.write( "1,2,3,4,6,12\r
\n" ); document.write( "\n" ); document.write( "-1,-2,-3,-4,-6,-12\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 $\"12\"$ .\r
\n" ); document.write( "\n" ); document.write( "1*12 = 12
\n" ); document.write( "2*6 = 12
\n" ); document.write( "3*4 = 12
\n" ); document.write( "(-1)*(-12) = 12
\n" ); document.write( "(-2)*(-6) = 12
\n" ); document.write( "(-3)*(-4) = 12\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	12	1+12=13
2	6	2+6=8
3	4	3+4=7
-1	-12	-1+(-12)=-13
-2	-6	-2+(-6)=-8
-3	-4	-3+(-4)=-7

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\n" ); document.write( "\n" ); document.write( "From the table, we can see that the two numbers $\"-3\"$ and $\"-4\"$ add to $\"-7\"$ (the middle coefficient).\r
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\n" ); document.write( "\n" ); document.write( "So the two numbers $\"-3\"$ and $\"-4\"$ both multiply to $\"12\"$ and add to $\"-7\"$ \r
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\n" ); document.write( "\n" ); document.write( "Now replace the middle term $\"-7x\"$ with $\"-3x-4x\"$ . Remember, $\"-3\"$ and $\"-4\"$ add to $\"-7\"$ . So this shows us that $\"-3x-4x=-7x\"$ .\r
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\n" ); document.write( "\n" ); document.write( " $\"x%5E2%2Bhighlight%28-3x-4x%29%2B12\"$ Replace the second term $\"-7x\"$ with $\"-3x-4x\"$ .\r
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\n" ); document.write( "\n" ); document.write( " $\"%28x%5E2-3x%29%2B%28-4x%2B12%29\"$ Group the terms into two pairs.\r
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\n" ); document.write( "\n" ); document.write( " $\"x%28x-3%29%2B%28-4x%2B12%29\"$ Factor out the GCF $\"x\"$ from the first group.\r
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\n" ); document.write( "\n" ); document.write( " $\"x%28x-3%29-4%28x-3%29\"$ Factor out $\"4\"$ 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( " $\"%28x-4%29%28x-3%29\"$ Combine like terms. Or factor out the common term $\"x-3\"$ \r
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\n" ); document.write( "\n" ); document.write( "So $\"4%28x%5E2-7x%2B12%29\"$ then factors further to $\"4%28x-4%29%28x-3%29\"$ \r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So $\"4x%5E2-28x%2B48\"$ completely factors to $\"4%28x-4%29%28x-3%29\"$ .\r
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\n" ); document.write( "\n" ); document.write( "In other words, $\"4x%5E2-28x%2B48=4%28x-4%29%28x-3%29\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Note: you can check the answer by expanding $\"4%28x-4%29%28x-3%29\"$ to get $\"4x%5E2-28x%2B48\"$ or by graphing the original expression and the answer (the two graphs should be identical).\r
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\n" ); document.write( "\n" ); document.write( "If you need more help, email me at jim_thompson5910@hotmail.com\r
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\n" ); document.write( "\n" ); document.write( "Also, feel free to check out my tutoring website\r
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\n" ); document.write( "\n" ); document.write( "Jim \n" ); document.write( "

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