document.write( "Question 929593: solve equation: x^4+9x^2=-20 \n" ); document.write( "

Algebra.Com's Answer #564535 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"x%5E4%2B9x%5E2=-20\"$
\n" ); document.write( " $\"x%5E4%2B9x%5E2%2B20=0\"$
\n" ); document.write( "Substitute $\"u=y%5E2\"$
\n" ); document.write( " $\"u%5E2%2B9u%2B20=0\"$
\n" ); document.write( " $\"%28u%2B4%29%28u%2B5%29=0\"$
\n" ); document.write( "Two \"u\" solutions:
\n" ); document.write( " $\"u%2B4=0\"$
\n" ); document.write( " $\"u=-4\"$
\n" ); document.write( " $\"y%5E2=-4\"$
\n" ); document.write( " $\"y=2i\"$ and $\"y=-2i\"$
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( " $\"u%2B5=0\"$
\n" ); document.write( " $\"u=-5\"$
\n" ); document.write( " $\"y%5E2=-5\"$
\n" ); document.write( " $\"y=sqrt%285%29i\"$ and $\"y=-sqrt%285%29i\"$ \n" ); document.write( "

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