Question

(8√3-5)(8√3-5) ?

Answer 1

We know:
\[
(a-b)^2=(a-b)(a-b)=a^2-2ab+b^2
\]Which means that, by multiplying out, or using the formula:
\[
(8\sqrt{3})^2-2(8\sqrt{3})(5)+5^2=192-80\sqrt{3}+25=217-80\sqrt{3}
\]And we are done.