Question 774877
Take 1/2 of the coefficient of the {{{ x }}} term
and square it
{{{ x^2 + 7x + ( 7/2 )^2 }}}
{{{ x^2 + 7x + 49/4 }}}
add 49/4 to make it a perfect square trinomial
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check:
{{{ ( x + 7/2 )^2 }}}
{{{ x^2 + 7x + 49/4 }}}
OK