document.write( "Question 117766: How do you factor bē -20b+51 ? \n" ); document.write( "
Algebra.Com's Answer #85741 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "Looking at \"b%5E2-20b%2B51\" we can see that the first term is \"b%5E2\" and the last term is \"51\" where the coefficients are 1 and 51 respectively.\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient 1 and the last coefficient 51 to get 51. Now what two numbers multiply to 51 and add to the middle coefficient -20? Let's list all of the factors of 51:\r
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\n" ); document.write( "\n" ); document.write( "Factors of 51:\r
\n" ); document.write( "\n" ); document.write( "1,3,17,51\r
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\n" ); document.write( "\n" ); document.write( "-1,-3,-17,-51 ...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 51\r
\n" ); document.write( "\n" ); document.write( "1*51\r
\n" ); document.write( "\n" ); document.write( "3*17\r
\n" ); document.write( "\n" ); document.write( "(-1)*(-51)\r
\n" ); document.write( "\n" ); document.write( "(-3)*(-17)\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 -20? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -20\r
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First NumberSecond NumberSum
1511+51=52
3173+17=20
-1-51-1+(-51)=-52
-3-17-3+(-17)=-20
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\n" ); document.write( "\n" ); document.write( "From this list we can see that -3 and -17 add up to -20 and multiply to 51\r
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\n" ); document.write( "\n" ); document.write( "Now looking at the expression \"b%5E2-20b%2B51\", replace \"-20b\" with \"-3b%2B-17b\" (notice \"-3b%2B-17b\" adds up to \"-20b\". So it is equivalent to \"-20b\")\r
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\n" ); document.write( "\n" ); document.write( "\"b%5E2%2Bhighlight%28-3b%2B-17b%29%2B51\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's factor \"b%5E2-3b-17b%2B51\" by grouping:\r
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\n" ); document.write( "\n" ); document.write( "\"%28b%5E2-3b%29%2B%28-17b%2B51%29\" Group like terms\r
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\n" ); document.write( "\n" ); document.write( "\"b%28b-3%29-17%28b-3%29\" Factor out the GCF of \"b\" out of the first group. Factor out the GCF of \"-17\" out of the second group\r
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\n" ); document.write( "\n" ); document.write( "\"%28b-17%29%28b-3%29\" Since we have a common term of \"b-3\", we can combine like terms\r
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\n" ); document.write( "\n" ); document.write( "So \"b%5E2-3b-17b%2B51\" factors to \"%28b-17%29%28b-3%29\"\r
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\n" ); document.write( "\n" ); document.write( "So this also means that \"b%5E2-20b%2B51\" factors to \"%28b-17%29%28b-3%29\" (since \"b%5E2-20b%2B51\" is equivalent to \"b%5E2-3b-17b%2B51\")\r
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\n" ); document.write( "\n" ); document.write( "So \"b%5E2-20b%2B51\" factors to \"%28b-17%29%28b-3%29\"\r
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