Question

(3 \sqrt{2} -4 \sqrt{5} ) ^{2} 

Answer 1

$(3 \sqrt{2} -4 \sqrt{5} ) ^{2} = \\ (3 \sqrt{2} -4 \sqrt{5} )(3 \sqrt{2} -4 \sqrt{5} )= \\ (3 \sqrt{2} )^2+2(3 \sqrt{2} )(-4 \sqrt{5}) +(-4 \sqrt{5})^2= \\ 18-24 \sqrt{10} +80= \\ 98-24 \sqrt{10} = \\ 2(49-12 \sqrt{10} )$