document.write( "Question 9656: How do I completely factor $\"81x%5E4-16\"$ ? \n" ); document.write( "

Algebra.Com's Answer #5251 by Earlsdon(6294) $\"\"$ $\"About$

You can put this solution on YOUR website!
First, you need to recognise this as the difference of two squares, and this factors like:\r
\n" ); document.write( "\n" ); document.write( " $\"a%5E2-b%5E2+=+%28a%2Bb%29%28a-b%29\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"81x%5E4+-+16+=+%289x%5E2+-+4%29%289x%5E2+%2B+4%29\"$ \r
\n" ); document.write( "\n" ); document.write( "Again, you have the difference of two squares, so this will factor.\r
\n" ); document.write( "\n" ); document.write( " $\"%283x-2%29%283x%2B2%29%289x%5E2%2B4%29\"$ \r
\n" ); document.write( "\n" ); document.write( "If you really want to factor completely, the the sum of two squares can be factored: $\"%28a%5E2+%2B+b%5E2%29+=+%28a+-+bi%29%28a+%2B+bi%29\"$ where: $\"+i+=+sqrt%28-1%29\"$ \r
\n" ); document.write( "\n" ); document.write( "The complete factorisation then is: $\"%283x-2%29%283x%2B2%29%283x-2i%29%283x%2B2i%29\"$ \r
\n" ); document.write( "\n" ); document.write( "If you are not yet into complex numbers, then leave it at: $\"%283x-2%29%283x%2B2%29%289x%5E2%2B4%29\"$
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