Question 660769
 {{{ (x + sqrt(a))(x - sqrt(a)) > 0 }}} 
Just looking at the signs of the 2 factors,
Neither factor can be {{{ 0 }}}
These 2 cases work:
(+) * (+) >0
( - ) * ( - ) > 0
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These don't work:
(+) * (-)
( - ) * (+)
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The 1st case:
(+) * (+) >0
{{{ x + sqrt(a) > 0 }}}
{{{ x > -sqrt(a) }}}
and
{{{ x - sqrt(a) > 0 }}}
{{{ x > sqrt(a) }}}
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Both of these have to be true. They are only
true if the 1st is true, so {{{ x > -sqrt(a) }}}
must hold
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The 2nd case
(-)*(-) >0
{{{ x + sqrt(a) < 0 }}}
{{{ x < -sqrt(a) }}}
and
{{{ x - sqrt(a) < 0 }}}
{{{ x < sqrt(a) }}}
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Both of these have to be true. They are only true
if {{{ x < -sqrt(a) }}}
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so, {{{ x < -sqrt(a) }}} or {{{ x > sqrt(a) }}}
since either of the 2 cases works