Question 960057
{{{ -2x - 99 + x^2 }}}
I'm guessing you want the roots
{{{ x^2 - 2x - 99 = 0 }}}
Complete the square
{{{ x^2 - 2x  + ( 2/2)^2 = 99 + ( 2/2 )^2 }}}
{{{ x^2 - 2x + 1 = 99 + 1 }}}
{{{ ( x - 1 )^2 = 10^2 }}}
Take the square root of both sides
{{{ x - 1 = 10 }}}
{{{ x = 11 }}}
and, take the negative square root of {{{ 10 }}},
{{{ x - 1 = -10 }}}
{{{ x = -9 }}}
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{{{ x = 11}}} and
{{{ x = -9 }}} are the roots
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check:
{{{ ( x + 9 )*( x - 11 ) = 0 }}}
{{{ x^2 - 2x - 99 = 0 }}}
OK