document.write( "Question 1012024: Simplify the expression by using a double-angle formula.
\n" ); document.write( "2cos^2 y/3-1 \n" ); document.write( "

Algebra.Com's Answer #627858 by ValorousDawn(53) $\"\"$ $\"About$

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Recall that $\"cos%282x%29=2cos%5E2%28x%29-1\"$
\n" ); document.write( "Set the equation equal to the one given.\r
\n" ); document.write( "\n" ); document.write( " $\"2cos%5E2%28x%29-1=2cos%5E2%28y%2F3%29-1\"$
\n" ); document.write( " $\"x=y%2F3\"$ \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Then substitute.
\n" ); document.write( " $\"2cos%5E2%28x%29-1=cos%282x%29\"$
\n" ); document.write( " $\"2cos%5E2%28y%2F3%29-1=cos%282y%2F3%29\"$ \n" ); document.write( "

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