document.write( "Question 692969: solve by substituting. x^-2-6x^-1=-4. hint: u=x^-1 \n" ); document.write( "

Algebra.Com's Answer #427173 by jim_thompson5910(35256) $\"\"$ $\"About$

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u=x^-1\r
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\n" ); document.write( "\n" ); document.write( "u^2=x^-2\r
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\n" ); document.write( "\n" ); document.write( "So\r
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\n" ); document.write( "\n" ); document.write( "x^-2-6x^-1=-4\r
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\n" ); document.write( "\n" ); document.write( "becomes\r
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\n" ); document.write( "\n" ); document.write( "u^2-6u = -4\r
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\n" ); document.write( "\n" ); document.write( "which turns into \r
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\n" ); document.write( "\n" ); document.write( "u^2 - 6u + 4 = 0\r
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\n" ); document.write( "\n" ); document.write( "Now use the quadratic formula to solve for 'u'. Once you have two solutions for 'u', use them to find the two solutions for 'x'.\r
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