document.write( "Question 139520: What do I solve this by factoring?\r
\n" ); document.write( "\n" ); document.write( "49x^2 - 14x - 3\r
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Algebra.Com's Answer #101719 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Looking at \"49x%5E2-14x-3\" we can see that the first term is \"49x%5E2\" and the last term is \"-3\" where the coefficients are 49 and -3 respectively.\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient 49 and the last coefficient -3 to get -147. Now what two numbers multiply to -147 and add to the middle coefficient -14? Let's list all of the factors of -147:\r
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\n" ); document.write( "\n" ); document.write( "Factors of -147:\r
\n" ); document.write( "\n" ); document.write( "1,3,7,21,49,147\r
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\n" ); document.write( "\n" ); document.write( "-1,-3,-7,-21,-49,-147 ...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 -147\r
\n" ); document.write( "\n" ); document.write( "(1)*(-147)\r
\n" ); document.write( "\n" ); document.write( "(3)*(-49)\r
\n" ); document.write( "\n" ); document.write( "(7)*(-21)\r
\n" ); document.write( "\n" ); document.write( "(-1)*(147)\r
\n" ); document.write( "\n" ); document.write( "(-3)*(49)\r
\n" ); document.write( "\n" ); document.write( "(-7)*(21)\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 -14? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -14\r
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First NumberSecond NumberSum
1-1471+(-147)=-146
3-493+(-49)=-46
7-217+(-21)=-14
-1147-1+147=146
-349-3+49=46
-721-7+21=14
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\n" ); document.write( "\n" ); document.write( "From this list we can see that 7 and -21 add up to -14 and multiply to -147\r
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\n" ); document.write( "\n" ); document.write( "Now looking at the expression \"49x%5E2-14x-3\", replace \"-14x\" with \"7x%2B-21x\" (notice \"7x%2B-21x\" adds up to \"-14x\". So it is equivalent to \"-14x\")\r
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\n" ); document.write( "\n" ); document.write( "\"49x%5E2%2Bhighlight%287x%2B-21x%29%2B-3\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's factor \"49x%5E2%2B7x-21x-3\" by grouping:\r
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\n" ); document.write( "\n" ); document.write( "\"%2849x%5E2%2B7x%29%2B%28-21x-3%29\" Group like terms\r
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\n" ); document.write( "\n" ); document.write( "\"7x%287x%2B1%29-3%287x%2B1%29\" Factor out the GCF of \"7x\" out of the first group. Factor out the GCF of \"-3\" out of the second group\r
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\n" ); document.write( "\n" ); document.write( "\"%287x-3%29%287x%2B1%29\" Since we have a common term of \"7x%2B1\", we can combine like terms\r
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\n" ); document.write( "\n" ); document.write( "So \"49x%5E2%2B7x-21x-3\" factors to \"%287x-3%29%287x%2B1%29\"\r
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\n" ); document.write( "\n" ); document.write( "So this also means that \"49x%5E2-14x-3\" factors to \"%287x-3%29%287x%2B1%29\" (since \"49x%5E2-14x-3\" is equivalent to \"49x%5E2%2B7x-21x-3\")\r
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\n" ); document.write( "\n" ); document.write( "\"%287x-3%29%287x%2B1%29=0\" Set the factorization equal to zero\r
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\n" ); document.write( "\n" ); document.write( "Now set each factor equal to zero:\r
\n" ); document.write( "\n" ); document.write( "\"7x-3=0\" or \"7x%2B1=0\" \r
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\n" ); document.write( "\n" ); document.write( "\"x=3%2F7\" or \"x=-1%2F7\" Now solve for x in each case\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So our solutions are\r
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\n" ); document.write( "\n" ); document.write( " \"x=3%2F7\" or \"x=-1%2F7\" \r
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