document.write( "Question 267203: I am trying to help my child with her homework. So, if you can explain it to me, maybe I can explain it to her.....without GIVING her the answer!\r
\n" ); document.write( "\n" ); document.write( "Find all of the zeros of the function:
\n" ); document.write( "\"h%28x%29=x%5E4-15x%5E3%2B70x%5E2-70x-156\"\r
\n" ); document.write( "\n" ); document.write( "I know how to figure out how many positive and negative zeros, but I don't understand how to figure out how many imaginary zeros. Then I don't know how to find all of the zeros.
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Algebra.Com's Answer #196176 by drk(1908)\"\" \"About 
You can put this solution on YOUR website!
\"h%28x%29=x%5E4-15x%5E3%2B70x%5E2-70x-156\"
\n" ); document.write( "first we use a technique called P-N-I This gives us the positive negative and imaginary zero combinations
\n" ); document.write( "P . . . N . . . I
\n" ); document.write( "3 . . . 1 . . . 0
\n" ); document.write( "1 . . . .1 . . . 2
\n" ); document.write( "So, I see that we must have 1 negative root somewhere.
\n" ); document.write( "Next I apply synthetic division to get roots.
\n" ); document.write( "-1 // 1 . . . . -15 . . . . 70 . . . . -70 . . . . -156
\n" ); document.write( " . . . . . . . . . . .-1 . . . . 16 . . . . .-86 . . . . 156
\n" ); document.write( " . . . . .1 . . . . .-16 . . . 86 . . . . .-156 . . . .0
\n" ); document.write( "and then
\n" ); document.write( "6// 1 . . . . -16 . . . . 86 . . . . -156
\n" ); document.write( " . . . . . . . . . . 6 . . . . -60 . . . .156
\n" ); document.write( " . . . . .1 . . . -10 . . . 26 . . . . .0
\n" ); document.write( "So we know that -1 and 6 are roots.
\n" ); document.write( "Now we can factor x^2 - 10x + 26 using the quadratic as
\n" ); document.write( "\"x+=+%2810+%2B-+sqrt%28+100-4%2A1%2A26+%29%29%2F%282%29+\"
\n" ); document.write( "and then
\n" ); document.write( "\"x+=+%2810+%2B-+sqrt%28-4%29%29%2F%282%29+\"
\n" ); document.write( "which gives us imaginary answers of
\n" ); document.write( "\"x+=+%285+%2B-+i%29+\"
\n" ); document.write( "-----
\n" ); document.write( "So, in total we have the following roots:
\n" ); document.write( "-6, 6, and 5 +-i
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