Question 947605
{{{ x^2  - 9x + 18 = 0 }}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{ a = 1 }}}
{{{ b = -9 }}}
{{{ c = 18 }}}
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{{{x = (-(-9) +- sqrt( (-9)^2 - 4*1*18 ))/(2*1) }}}
{{{x = ( 9 +- sqrt( 81 - 72 ))/2 }}}
{{{ x = ( 9 +- sqrt( 9 ) ) / 2 }}}
{{{ x = ( 9 + 3 ) / 2 }}}
{{{ x = 12/2 }}}
{{{ x = 6 }}}
And, using the negative square root,
{{{ x = ( 9 - 3 ) / 2 }}}
{{{ x = 6/2 }}}
{{{ x = 3 }}}
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check:
The factors are:
{{{ ( x - 6 )*( x - 3 ) = x^2 - 9x + 18 }}}
OK