document.write( "Question 273645: solve tby completing the square: 4x^2-20x+21=0. Factor the polynomial \n" ); document.write( "

Algebra.Com's Answer #199880 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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solve by completing the square: 4x^2-20x+21=0. Factor the polynomial
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\n" ); document.write( "4x^2 - 20x + ___ = -21
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\n" ); document.write( "We need the coefficient of x^2 to be 1, divide equation 4, results:
\n" ); document.write( "x^2 - 5x + ____ = $\"-21%2F4\"$
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\n" ); document.write( "To complete the square (5/2)^2 = 25/4
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\n" ); document.write( "x^2 - 5x + $\"25%2F4\"$ = $\"-21%2F4\"$ + $\"25%2F4\"$
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\n" ); document.write( "x^2 - 5x + $\"25%2F4\"$ = $\"4%2F4\"$
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\n" ); document.write( "x^2 - 5x + $\"25%2F4\"$ = 1
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\n" ); document.write( "(x - $\"5%2F2\"$ )^2 = 1
\n" ); document.write( "Find the square root of both sides
\n" ); document.write( "x - $\"5%2F2\"$ = +/- $\"sqrt%281%29\"$
\n" ); document.write( "two solutions
\n" ); document.write( "x = $\"5%2F2\"$ + 1
\n" ); document.write( "and
\n" ); document.write( "x = $\"5%2F2\"$ - 1
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\n" ); document.write( "x = $\"7%2F2\"$ and $\"3%2F2\"$ \r
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