document.write( "Question 579927: x^4+3x^2-28=0
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Algebra.Com's Answer #371259 by KMST(5328) $\"\"$ $\"About$

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Factoring we get
\n" ); document.write( " $\"x%5E4%2B3x%5E2-28=0\"$ --> $\"%28x%5E2%2B7%29%28x%5E2-4%29=0\"$
\n" ); document.write( "If you do not \"see\"\" that factoring make the change of variable $\"y=x%5E2\"$
\n" ); document.write( "to get $\"y%5E2%2B3y-28=0\"$ . Then you can factor or apply the quadratic formula to find the roots, and hence the factors.
\n" ); document.write( " $\"%28x%5E2%2B7%29%28x%5E2-4%29=0\"$ --> $\"%28x%5E2%2B7%29%28x%2B2%29%28x-2%29=0\"$
\n" ); document.write( " $\"x%5E2%2B7=0\"$ does not yield any real roots. The real roots come from making zero the other 2 factors:
\n" ); document.write( " $\"highlight%28x=-2%29\"$ and $\"highlight%28x=2%29\"$ \n" ); document.write( "

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