Question

Calculati:
(2√6-√5)(√6-2√5)
(2√3-5)(√3+7)

Answer 1

$(2 \sqrt{6} - \sqrt{5} )( \sqrt{6} -2 \sqrt{5} )=12-4 \sqrt{30} - \sqrt{30} +10=22-5 \sqrt{30} \\ (2 \sqrt{3} -5)( \sqrt{3} +7)=6+14 \sqrt{3} -5 \sqrt{3} -35=-29+9 \sqrt{3}$