document.write( "Question 255903: 15t^4-34t^2+15=0??? \n" ); document.write( "

Algebra.Com's Answer #188102 by drk(1908) $\"\"$ $\"About$

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We are going to solve with a \"dummy variable\" of U = t^2.
\n" ); document.write( "SInce u = t^2, U^2 = t^4. By substitution of our dummy variable, we get
\n" ); document.write( " $\"15U%5E2+-+34U+%2B+15+=+0\"$
\n" ); document.write( "This looks more familiar and we apply factoring to get
\n" ); document.write( " $\"%285U+-3%29%283U-5%29+=+0\"$
\n" ); document.write( "Solve each for U to get
\n" ); document.write( " $\"5U-3+=+0\"$
\n" ); document.write( " $\"U+=+3%2F5\"$
\n" ); document.write( "and
\n" ); document.write( " $\"3U-5+=+0\"$
\n" ); document.write( " $\"U+=+5%2F3\"$
\n" ); document.write( "resub t^2 for U to get
\n" ); document.write( " $\"t%5E2+=+3%2F5\"$
\n" ); document.write( " $\"t+=+sqrt%283%2F5%29\"$
\n" ); document.write( "and
\n" ); document.write( " $\"t%5E2+=+5%2F3\"$
\n" ); document.write( " $\"t+=+sqrt%285%2F3%29\"$ \n" ); document.write( "

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