document.write( "Question 754133: Factor
\n" ); document.write( "x^4 - 81 \n" ); document.write( "

Algebra.Com's Answer #458812 by nerdybill(7384) $\"\"$ $\"About$

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x^4 - 81
\n" ); document.write( "can be rewritten as:
\n" ); document.write( "(x^2)^2 - (9)^2
\n" ); document.write( "this is a \"difference of squares\" (special case factors to):
\n" ); document.write( "(x^2 - 9)(x^2 + 9)
\n" ); document.write( "But, the left term can be rewritten as:
\n" ); document.write( "(x^2 - 3^2)(x^2 + 9)
\n" ); document.write( "another \"difference of squares\":
\n" ); document.write( "(x-3)(x+3)(x^2+9) (final factored form) \n" ); document.write( "

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