Bài 1:
\(\left(3\sqrt{2}+4\sqrt{3}\right)^2-\left(2\sqrt{2}+3\sqrt{3}\right)^2\)
\(=\left(3\sqrt{2}\right)^2+2\cdot3\sqrt{2}\cdot4\sqrt{3}+\left(4\sqrt{3}\right)^2-\left(2\sqrt{2}\right)^2-2\cdot2\sqrt{2}\cdot3\sqrt{3}-\left(3\sqrt{3}\right)^2\)
\(=18+24\sqrt{6}+48-8-12\sqrt{6}-27\)
\(=12\sqrt{6}+31\)