document.write( "Question 515414: factor completely 112b^2+392bg+343g^2 \n" ); document.write( "
Algebra.Com's Answer #343956 by drcole(72)\"\" \"About 
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To factor \"112+b%5E2+%2B+392+b+g+%2B+343+g%5E2+\", we first notice that all of the coefficients are divisible by 7, so we factor 7 out of each term:\r
\n" ); document.write( "\n" ); document.write( "\"+7%2816+b%5E2+%2B+56++b+g+%2B+49+g%5E2%29+\"\r
\n" ); document.write( "\n" ); document.write( "There are no other common factors of the coefficients. Now we need to find two numbers whose product is (16)(49) = 784 and whose sum is 56. Let's write out some possible ways to factor 784 and look at the sum of the factors:\r
\n" ); document.write( "\n" ); document.write( "(1)(784) sum = 785
\n" ); document.write( "(2)(392) sum = 394
\n" ); document.write( "(4)(196) sum = 200
\n" ); document.write( "(7)(112) sum = 119
\n" ); document.write( "(8)(98) sum = 106
\n" ); document.write( "(14)(56) sum = 70
\n" ); document.write( "(16)(49) sum = 65
\n" ); document.write( "(28)(28) sum = 56 <--- this works!\r
\n" ); document.write( "\n" ); document.write( "So we've found our combination. We can rewrite the quadratic expression using these two factors:\r
\n" ); document.write( "\n" ); document.write( "\"7%2816+b%5E2+%2B+28+b+g+%2B+28+b+g+%2B+343+g%5E2%29\"\r
\n" ); document.write( "\n" ); document.write( "Now we can factor the quadratic by grouping. The greatest common factor of \"16+b%5E2\" and \"28+b+g\" is \"4b\", so we factor that out of the first two terms:\r
\n" ); document.write( "\n" ); document.write( "\"7%284b%28+4b+%2B+7g%29+%2B+28+b+g+%2B+343+g%5E2%29\"\r
\n" ); document.write( "\n" ); document.write( "The greatest common factor of \"28+b+g\" and \"343+g%5E2\" is \"7g\", so we factor this out of the last two terms:\r
\n" ); document.write( "\n" ); document.write( "\"7%284b%284b+%2B+7g%29+%2B+7g%284b+%2B+7g%29%29\"\r
\n" ); document.write( "\n" ); document.write( "Now we factor \"4b+%2B+7g\" out of both terms:\r
\n" ); document.write( "\n" ); document.write( "\"7%284b+%2B+7g%29%284b+%2B+7g%29+=+7%284b+%2B+7g%29%5E2\"\r
\n" ); document.write( "\n" ); document.write( "This completes the factorization.
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