document.write( "Question 144025: Factor:
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Algebra.Com's Answer #104822 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"5x%5E3%2B20x%5E2%2B20x\" Start with the given expression\r
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\n" ); document.write( "\n" ); document.write( "\"5x%28x%5E2%2B4x%2B4%29\" Factor out the GCF \"5x\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's focus on the inner expression \"x%5E2%2B4x%2B4\"\r
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\n" ); document.write( "\n" ); document.write( "Looking at \"1x%5E2%2B4x%2B4\" we can see that the first term is \"1x%5E2\" and the last term is \"4\" where the coefficients are 1 and 4 respectively.\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient 1 and the last coefficient 4 to get 4. Now what two numbers multiply to 4 and add to the middle coefficient 4? Let's list all of the factors of 4:\r
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\n" ); document.write( "\n" ); document.write( "Factors of 4:\r
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\n" ); document.write( "\n" ); document.write( "-1,-2 ...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 4\r
\n" ); document.write( "\n" ); document.write( "1*4\r
\n" ); document.write( "\n" ); document.write( "2*2\r
\n" ); document.write( "\n" ); document.write( "(-1)*(-4)\r
\n" ); document.write( "\n" ); document.write( "(-2)*(-2)\r
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\n" ); document.write( "\n" ); document.write( "note: remember two negative numbers multiplied together make a positive number\r
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\n" ); document.write( "\n" ); document.write( "Now which of these pairs add to 4? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 4\r
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First NumberSecond NumberSum
141+4=5
222+2=4
-1-4-1+(-4)=-5
-2-2-2+(-2)=-4
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\n" ); document.write( "\n" ); document.write( "From this list we can see that 2 and 2 add up to 4 and multiply to 4\r
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\n" ); document.write( "\n" ); document.write( "Now looking at the expression \"1x%5E2%2B4x%2B4\", replace \"4x\" with \"2x%2B2x\" (notice \"2x%2B2x\" adds up to \"4x\". So it is equivalent to \"4x\")\r
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\n" ); document.write( "\n" ); document.write( "\"1x%5E2%2Bhighlight%282x%2B2x%29%2B4\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's factor \"1x%5E2%2B2x%2B2x%2B4\" by grouping:\r
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\n" ); document.write( "\n" ); document.write( "\"%281x%5E2%2B2x%29%2B%282x%2B4%29\" Group like terms\r
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\n" ); document.write( "\n" ); document.write( "\"x%28x%2B2%29%2B2%28x%2B2%29\" Factor out the GCF of \"x\" out of the first group. Factor out the GCF of \"2\" out of the second group\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%28x%2B2%29\" Since we have a common term of \"x%2B2\", we can combine like terms\r
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\n" ); document.write( "\n" ); document.write( "So \"1x%5E2%2B2x%2B2x%2B4\" factors to \"%28x%2B2%29%28x%2B2%29\"\r
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\n" ); document.write( "\n" ); document.write( "So this also means that \"1x%5E2%2B4x%2B4\" factors to \"%28x%2B2%29%28x%2B2%29\" (since \"1x%5E2%2B4x%2B4\" is equivalent to \"1x%5E2%2B2x%2B2x%2B4\")\r
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\n" ); document.write( "\n" ); document.write( "note: \"%28x%2B2%29%28x%2B2%29\" is equivalent to \"%28x%2B2%29%5E2\" since the term \"x%2B2\" occurs twice. So \"1x%5E2%2B4x%2B4\" also factors to \"%28x%2B2%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "So our expression goes from \"5x%28x%5E2%2B4x%2B4%29\" and factors further to \"5x%28x%2B2%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "So \"5x%5E3%2B20x%5E2%2B20x\" factors to \"5x%28x%2B2%29%5E2\"\r
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