<PRE><B>Question 158204</B>
{{{(-7*sqrt(11)-sqrt(7))(sqrt(7)-10*sqrt(11))}}} Start with the given expression.



{{{-7*sqrt(11)*sqrt(7)- 7*sqrt(11)(-10*sqrt(11)) -sqrt(7)*sqrt(7) - sqrt(7)(-10*sqrt(11))}}} FOIL



{{{-7*sqrt(77)+70*sqrt(121) -sqrt(49) +10*sqrt(77)}}} Multiply



{{{-7*sqrt(77)+70*(11)-7+10*sqrt(77)}}} Take the square root of 121 to get 11. Take the square root of 49 to get 7. 



{{{-7*sqrt(77)+770-7+10*sqrt(77)}}} Multiply



{{{763+3*sqrt(77)}}} Combine like terms



So {{{(-7*sqrt(11)-sqrt(7))(sqrt(7)-10*sqrt(11))=763+3*sqrt(77)}}}


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