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document.write( "

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document.write( "

\r\n" );
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document.write( "If A,B,C,D are the only values that make the above true for all allowable values,\r\n" );
document.write( "then they are also the only values that will make the equation below true as\r\n" );
document.write( "well. It is formed by clearing of fractions, and we notice that x can take on\r\n" );
document.write( "values in this which would cause the equation above to be undefined. In fact,\r\n" );
document.write( "those are the very values we are going to substitute for x.\r\n" );
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document.write( "

\r\n" );
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document.write( "We substitute x= -3 and only the second term on the right is not 0.\r\n" );
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document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

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document.write( "

\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "----------------------\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "We substitute x= 0 and only the third term on the right is not 0.\r\n" );
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document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

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document.write( "

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document.write( "\r\n" );
document.write( "----------------------\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "We substitute x= 1 and only the first term on the right is not 0.\r\n" );
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document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "----------------------\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "We substitute x=-1 and only the last term on the right is not 0.\r\n" );
document.write( "\r\n" );
document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "

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document.write( "
\r\n" );
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document.write( "

\r\n" );
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document.write( "So the answer is:\r\n" );
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document.write( "

\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" );
document.write( "