Question 516154
{{{ ( 3sqrt2 - 6*sqrt7 )*( 4*sqrt2 + 8*sqrt7 ) }}}
Follow the rule:
{{{ ( a - b )*( c + d ) = a*c - b*c + a*d - b*d }}}
{{{ 12*sqrt(2)*sqrt(2) - 24*sqrt(7)*sqrt(2) + 24*sqrt(7)*sqrt(2) - 48*sqrt(7)*sqrt(7) }}}
{{{ 12*sqrt(4) - 24*sqrt(14) + 24*sqrt(14) - 48*sqrt(49) }}}
{{{ 12*2 - 48*7 }}}
{{{ 24 - 336 }}}
{{{ -312 }}}
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That is if only the positive square roots are required.
Usually that's true.