document.write( "Question 256125: how do you factor the polynomial x^4-8x^2-9 \n" ); document.write( "
Algebra.Com's Answer #188290 by drk(1908)\"\" \"About 
You can put this solution on YOUR website!
We are given
\n" ); document.write( "(i) \"x%5E4-8x%5E2-9\"
\n" ); document.write( "step 1 - set up a dummy variable like U = x^2. If U = x^2, then U^2 = x^4.
\n" ); document.write( "Step 2 - substitute the dummy variable into the equation to get
\n" ); document.write( "(ii) \"U%5E2+-8U+-9\"
\n" ); document.write( "step 3 - factoring we get
\n" ); document.write( "(iii) \"%28U-9%29%28U%2B1%29\"
\n" ); document.write( "step 4 - replace U with x^2 to get
\n" ); document.write( "(iv)\"%28x%5E2-9%29%28x%5E2%2B1%29\"
\n" ); document.write( "step 5 - notice the difference of squares. We can factor that to get
\n" ); document.write( "(v) \"%28x-3%29%28x%2B3%29%28x%5E2%2B1%29\"
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