document.write( "Question 475872: The equation x⁴-2x²-16x-15 has four roots. If two of the roots are real and equal to x=-1 and x=3, by a process of long division and solving a quadratic equation find the two complex roots \n" ); document.write( "
Algebra.Com's Answer #326414 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
given:
\n" ); document.write( "\"+x+=+-1+\"
\n" ); document.write( "\"+x+%2B+1+=+0+\"
\n" ); document.write( "and
\n" ); document.write( "\"+x+=+3+\"
\n" ); document.write( "\"+x+-+3+=+0+\"
\n" ); document.write( "--------------
\n" ); document.write( "Complex roots come in pairs
\n" ); document.write( "of the form \"+a+%2B+bi+\"
\n" ); document.write( "and \"+a+-+bi+\"
\n" ); document.write( "I can factor out \"+%28x+%2B+1%29%2A%28x+-+3%29+\"
\n" ); document.write( "\"+%28x+%2B+1%29%2A%28x+-+3%29+=+x%5E2+-+2x+-+3+\"
\n" ); document.write( "\"+%28x%5E4+-+2x%5E2+-+16x+-+15%29+%2F+%28x%5E2+-+2x+-+3%29+=+x%5E2+%2B+2x+%2B+5+\"
\n" ); document.write( "I can use quadratic formula now
\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( "\"+a+=+1+\"
\n" ); document.write( "\"+b+=+2+\"
\n" ); document.write( "\"+c+=+5+\"
\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+2%5E2-4%2A1%2A5+%29%29%2F%282%2A1%29+\"
\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+4+-+20+%29%29%2F2+\"
\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+-16+%29%29%2F2+\"
\n" ); document.write( "\"x+=+%28-2+%2B+4i%29%2F2+\"
\n" ); document.write( "\"+x+=+-1+%2B+2i+\" 1st root
\n" ); document.write( "and
\n" ); document.write( "\"x+=+%28-2+-+4i%29%2F2+\"
\n" ); document.write( "\"+x+=+-1+-+2i+\" 2nd root\r
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