document.write( "Question 168806: Factor 2x^2y^3 + 3xy^2 - 5xy \n" ); document.write( "
Algebra.Com's Answer #124450 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"2x%5E2y%5E3%2B3xy%5E2-5xy\" Start with the given expression\r
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\n" ); document.write( "\n" ); document.write( "\"xy%282xy%5E2%2B3y-5%29\" Factor out the GCF \"xy\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's focus on the inner expression \"2xy%5E2%2B3y-5\"\r
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\n" ); document.write( "\n" ); document.write( "Looking at \"2xy%5E2%2B3y-5\" we can see that the first term is \"2xy%5E2\" and the last term is \"-5\" where the coefficients are 2 and -5 respectively.\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient 2 and the last coefficient -5 to get -10. Now what two numbers multiply to -10 and add to the middle coefficient 3? Let's list all of the factors of -10:\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
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\n" ); document.write( "\n" ); document.write( "-1,-2,-5,-10 ...List the negative factors as well. 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)\r
\n" ); document.write( "\n" ); document.write( "(2)*(-5)\r
\n" ); document.write( "\n" ); document.write( "(-1)*(10)\r
\n" ); document.write( "\n" ); document.write( "(-2)*(5)\r
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\n" ); document.write( "\n" ); document.write( "note: remember, the product of a negative and a positive number is a negative number\r
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\n" ); document.write( "\n" ); document.write( "Now which of these pairs add to 3? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 3\r
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First NumberSecond NumberSum
1-101+(-10)=-9
2-52+(-5)=-3
-110-1+10=9
-25-2+5=3
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\n" ); document.write( "\n" ); document.write( "From this list we can see that -2 and 5 add up to 3 and multiply to -10\r
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\n" ); document.write( "\n" ); document.write( "Now looking at the expression \"2xy%5E2%2B3y-5\", replace \"3y\" with \"-2y%2B5y\" (notice \"-2y%2B5y\" adds up to \"3y\". So it is equivalent to \"3y\")\r
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\n" ); document.write( "\n" ); document.write( "\"2xy%5E2%2Bhighlight%28-2y%2B5y%29%2B-5\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's factor \"2xy%5E2-2y%2B5y-5\" by grouping:\r
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\n" ); document.write( "\n" ); document.write( "\"%282xy%5E2-2y%29%2B%285y-5%29\" Group like terms\r
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\n" ); document.write( "\n" ); document.write( "\"2y%28xy-1%29%2B5%28y-1%29\" Factor out the GCF of \"2y\" out of the first group. Factor out the GCF of \"5\" out of the second group\r
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\n" ); document.write( "\n" ); document.write( "So this also means that \"2xy%5E2%2B3y-5\" factors to \"%282y%2B5%29%28xy-1%29\" (since \"2xy%5E2%2B3y-5\" is equivalent to \"2xy%5E2-2y%2B5y-5\")\r
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\n" ); document.write( "\n" ); document.write( "So our expression goes from \"xy%282xy%5E2%2B3y-5%29\" and factors further to \"xy%282y%2B5%29%28xy-1%29\"\r
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\n" ); document.write( "\n" ); document.write( "So \"2x%5E2y%5E3%2B3xy%5E2-5xy\" factors to \"xy%282y%2B5%29%28xy-1%29\"\r
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