document.write( "Question 337025: I need help solving the following equation for 0(<=) X (<=)2pi\r
\n" ); document.write( "\n" ); document.write( "2cos^2X - 3cosX-2=0\r
\n" ); document.write( "\n" ); document.write( "Thank you! \n" ); document.write( "

Algebra.Com's Answer #241599 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
Use a substitution,
\n" ); document.write( " $\"u=cos%28x%29\"$
\n" ); document.write( " $\"2u%5E2-3u-2=0\"$
\n" ); document.write( " $\"%282u%2B1%29%28u-2%29=0\"$
\n" ); document.write( "Two solutions:
\n" ); document.write( " $\"2u%2B1=0\"$
\n" ); document.write( " $\"2u=-1\"$
\n" ); document.write( " $\"u=-1%2F2\"$
\n" ); document.write( " $\"cos%28x%29=-1%2F2\"$
\n" ); document.write( " $\"x=%282%2Api%29%2F3\"$ , $\"%284%2Api%29%2F3\"$
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( " $\"u-2=0\"$
\n" ); document.write( " $\"u=2\"$
\n" ); document.write( " $\"cos%28x%29=2\"$
\n" ); document.write( "No solutions.
\n" ); document.write( " \n" ); document.write( "

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