document.write( "Question 1129941: Degree 4; zeros: 5+5i; -4 multiplicity 2 \n" ); document.write( "
Algebra.Com's Answer #746559 by greenestamps(13206)\"\" \"About 
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\n" ); document.write( "The statement of the problem is not complete. Without the stated requirement that the polynomial have rational coefficients, the fourth root could be any complex number.

\n" ); document.write( "Assuming rational coefficients, the four roots are -4, -4, 5+5i, and 5-5i.

\n" ); document.write( "The quadratic polynomial with roots -4 and -4 is

\n" ); document.write( "\"%28x%2B4%29%28x%2B4%29+=+x%5E2%2B8x%2B16\"

\n" ); document.write( "The quadratic polynomial with roots 5+5i and 5-5i is

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\n" ); document.write( "An alternative way to find the quadratic polynomial with roots 5+5i and 5-5i is to use the fact that the quadratic polynomial ax^2+bx+c has roots whose sum is -b/a and whose product is c/a.

\n" ); document.write( "The sum of the roots 5+5i and 5-5i is 10; so the linear coefficient in the quadratic polynomial is -10.

\n" ); document.write( "The product of the roots 5+5i and 5-5i is 25-25i^2 = 25+25 = 50; so the constant in the quadratic polynomial is 50.

\n" ); document.write( "Then the quadratic polynomial with roots 5+5i and 5-5i is x^2-10x+50.

\n" ); document.write( "Finally the polynomial with roots -4, -4, 5+5i and 5-5i is

\n" ); document.write( "\"%28x%5E2%2B8x%2B16%29%28x%5E2-10x%2B50%29+=+x%5E4-2x%5E3-14x%5E2%2B240x%2B800\"
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