document.write( "Question 140955This question is from textbook college algebra
\n" ); document.write( ": Can I please get assistance with the following problem?\r
\n" ); document.write( "\n" ); document.write( "factor f(x) into linear factors given that k is a zero of f(x)
\n" ); document.write( "f(x)=x^3-6x^2-25x+150;k=5\r
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Algebra.Com's Answer #102611 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Since k=5 is a zero, this means that 5 is a test zero\r
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\n" ); document.write( "\n" ); document.write( "So break down \"f%28x%29=x%5E3-6x%5E2-25x%2B150\" by using synthetic division\r
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\n" ); document.write( "\n" ); document.write( "Set up the synthetic division table by placing the test zero in the upper left corner and placing the coefficients of the function to the right of the test zero.\n" ); document.write( "\n" ); document.write( "
5|1-6-25150
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\n" ); document.write( "\n" ); document.write( "Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 1)\r
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5|1-6-25150
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1
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\n" ); document.write( "\n" ); document.write( " Multiply 5 by 1 and place the product (which is 5) right underneath the second coefficient (which is -6)\r
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5|1-6-25150
|5
1
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\n" ); document.write( "\n" ); document.write( " Add 5 and -6 to get -1. Place the sum right underneath 5.\r
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5|1-6-25150
|5
1-1
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\n" ); document.write( "\n" ); document.write( " Multiply 5 by -1 and place the product (which is -5) right underneath the third coefficient (which is -25)\r
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5|1-6-25150
|5-5
1-1
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\n" ); document.write( "\n" ); document.write( " Add -5 and -25 to get -30. Place the sum right underneath -5.\r
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5|1-6-25150
|5-5
1-1-30
\r
\n" ); document.write( "\n" ); document.write( " Multiply 5 by -30 and place the product (which is -150) right underneath the fourth coefficient (which is 150)\r
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5|1-6-25150
|5-5-150
1-1-30
\r
\n" ); document.write( "\n" ); document.write( " Add -150 and 150 to get 0. Place the sum right underneath -150.\r
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5|1-6-25150
|5-5-150
1-1-300
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\n" ); document.write( "\n" ); document.write( "Since the last column adds to zero, we have a remainder of zero. This means \"x-5\" is a factor of \"x%5E3+-+6x%5E2+-+25x+%2B+150\"\r
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\n" ); document.write( "\n" ); document.write( "Now lets look at the bottom row of coefficients:\r
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\n" ); document.write( "\n" ); document.write( "The first 3 coefficients (1,-1,-30) form the quotient\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2+-+x+-+30\"\r
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\n" ); document.write( "\n" ); document.write( "So \"%28x%5E3+-+6x%5E2+-+25x+%2B+150%29%2F%28x-5%29=x%5E2+-+x+-+30\"\r
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\n" ); document.write( "\n" ); document.write( "You can use this online polynomial division calculator to check your work\r
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\n" ); document.write( "\n" ); document.write( "Basically \"x%5E3+-+6x%5E2+-+25x+%2B+150\" factors to \"%28x-5%29%28x%5E2+-+x+-+30%29\"\r
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\n" ); document.write( "\n" ); document.write( "Now lets break \"x%5E2+-+x+-+30\" down further\r
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\n" ); document.write( "\n" ); document.write( "Looking at \"x%5E2-x-30\" we can see that the first term is \"x%5E2\" and the last term is \"-30\" where the coefficients are 1 and -30 respectively.\r
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\n" ); document.write( "\n" ); document.write( "Now multiply the first coefficient 1 and the last coefficient -30 to get -30. Now what two numbers multiply to -30 and add to the middle coefficient -1? Let's list all of the factors of -30:\r
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\n" ); document.write( "\n" ); document.write( "Factors of -30:\r
\n" ); document.write( "\n" ); document.write( "1,2,3,5,6,10,15,30\r
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\n" ); document.write( "\n" ); document.write( "-1,-2,-3,-5,-6,-10,-15,-30 ...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 -30\r
\n" ); document.write( "\n" ); document.write( "(1)*(-30)\r
\n" ); document.write( "\n" ); document.write( "(2)*(-15)\r
\n" ); document.write( "\n" ); document.write( "(3)*(-10)\r
\n" ); document.write( "\n" ); document.write( "(5)*(-6)\r
\n" ); document.write( "\n" ); document.write( "(-1)*(30)\r
\n" ); document.write( "\n" ); document.write( "(-2)*(15)\r
\n" ); document.write( "\n" ); document.write( "(-3)*(10)\r
\n" ); document.write( "\n" ); document.write( "(-5)*(6)\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 -1? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -1\r
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First NumberSecond NumberSum
1-301+(-30)=-29
2-152+(-15)=-13
3-103+(-10)=-7
5-65+(-6)=-1
-130-1+30=29
-215-2+15=13
-310-3+10=7
-56-5+6=1
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\n" ); document.write( "\n" ); document.write( "From this list we can see that 5 and -6 add up to -1 and multiply to -30\r
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\n" ); document.write( "\n" ); document.write( "Now looking at the expression \"x%5E2-x-30\", replace \"-x\" with \"5x%2B-6x\" (notice \"5x%2B-6x\" adds up to \"-x\". So it is equivalent to \"-x\")\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2%2Bhighlight%285x%2B-6x%29%2B-30\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's factor \"x%5E2%2B5x-6x-30\" by grouping:\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%5E2%2B5x%29%2B%28-6x-30%29\" Group like terms\r
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\n" ); document.write( "\n" ); document.write( "\"x%28x%2B5%29-6%28x%2B5%29\" Factor out the GCF of \"x\" out of the first group. Factor out the GCF of \"-6\" out of the second group\r
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\n" ); document.write( "\n" ); document.write( "\"%28x-6%29%28x%2B5%29\" Since we have a common term of \"x%2B5\", we can combine like terms\r
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\n" ); document.write( "\n" ); document.write( "So \"x%5E2%2B5x-6x-30\" factors to \"%28x-6%29%28x%2B5%29\" which means that \"x%5E2-x-30\" factors to \"%28x-6%29%28x%2B5%29\"\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So \"x%5E3-6x%5E2-25x%2B150\" factors to \"%28x-5%29%28x-6%29%28x%2B5%29\"
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