b) Ta có: \(B=3\sqrt{50}-7\sqrt{8}+12\sqrt{18}\)
\(=15\sqrt{2}-14\sqrt{2}+36\sqrt{2}\)
\(=37\sqrt{2}\)
c) Ta có: \(C=2\sqrt{80}-2\sqrt{245}+2\sqrt{180}\)
\(=8\sqrt{5}-14\sqrt{5}+12\sqrt{5}\)
\(=6\sqrt{5}\)
d) Ta có: \(D=2\sqrt{12}-\sqrt{48}+3\sqrt{27}-\sqrt{108}\)
\(=4\sqrt{3}-4\sqrt{3}+9\sqrt{3}-6\sqrt{3}\)
\(=3\sqrt{3}\)