document.write( "Question 158768: 4x^4-16x^2+15=0, the answer I got was sqrt6/2, sgrt-6/2, sqrt10/2, sqrt-10/2, is that correct? \n" ); document.write( "
Algebra.Com's Answer #116999 by gonzo(654)\"\" \"About 
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i got \"x=%2Bsqrt%285%2F2%29\" and \"x=-sqrt%285%2F2%29\"
\n" ); document.write( "i also got \"x=%2Bsqrt%283%2F2%29\" and \"x=-sqrt%283%2F2%29\"
\n" ); document.write( "here's how.....
\n" ); document.write( "\"4%2Ax%5E4+-+16%2Ax+%2B+15+=+%282x%5E2-5%29%2A%282x%5E2-3%29+=+0\"
\n" ); document.write( "if the whole thing equals 0 then at least one of the factors must = 0.
\n" ); document.write( "solving for the first factor = 0, i get
\n" ); document.write( "\"%282%2Ax%5E2-5%29+=+0\" becomes \"%282x%5E2%29=5\" becomes \"x%5E2=%285%2F2%29\"
\n" ); document.write( "and
\n" ); document.write( "solving for the second factor = 0, i get
\n" ); document.write( "\"%282%2Ax%5E2-3%29+=+0\" becomes \"%282x%5E2%29=3\" becomes \"x%5E2=%283%2F2%29\"
\n" ); document.write( "plugging \"x%5E2=%285%2F2%29\" into the original equation, i get
\n" ); document.write( "\"4%2A%285%2F2%29%5E2+-+16%2A%285%2F2%29+%2B+15+=+0\"
\n" ); document.write( "this becomes
\n" ); document.write( "\"4%2A%2825%2F4%29+-+80%2F2+%2B+15+=+0\"
\n" ); document.write( "this becomes \"-15%2B15=0\" proving first factor is good.
\n" ); document.write( "plugging \"x%5E2=%283%2F2%29\" into the original equation, i get
\n" ); document.write( "\"4%2A%283%2F2%29%5E2+-+16%2A%283%2F2%29+%2B+15+=+0\"
\n" ); document.write( "this becomes
\n" ); document.write( "\"4%2A%289%2F4%29+-+48%2F2+%2B+15+=+0\"
\n" ); document.write( "this becomes \"-15%2B15=0\" proving second factor is good.
\n" ); document.write( "if \"x%5E2+=+%285%2F2%29\" and \"x%5E2+=+%283%2F2%29\" are the correct answers (proven above), then
\n" ); document.write( "x = +/- \"sqrt%285%2F2%29\" and x = +/- \"sqrt%283%2F2%29\" are the correct values for x.\r
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