Question 954853
Call the numbers {{{ a }}} and {{{ b }}}
{{{ a + b = x }}}
{{{ a*b = -12 }}}
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{{{ b = x - a }}}
By substitution:
{{{ a*( x - a ) = -12 }}}
{{{ a^2 - a*x - 12 = 0 }}}
{{{ ( a - 4 )*( a + 3 ) = 0 }}}
{{{ a = 4 }}}
and
{{{ a*b = -12 }}}
{{{ b = -12/a }}}
{{{ b = -12/4 }}}
{{{ b = -3 }}}
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The numbers are 4 and -3
check:
{{{ a + b = x }}}
{{{ 4 + -3 = x }}} 
{{{ x = 1 }}}
{{{ a*( x - a ) = -12 }}}
{{{ 4*( 1 - 4 ) = -12 }}}
{{{ 4*(-3) = -12 }}}
{{{ -12 = -12 }}}
OK