Bài 1:
\(A=5\sqrt{3}-\sqrt{12}+\sqrt{27}\)
\(=5\sqrt{3}-2\sqrt{3}+3\sqrt{3}\)
\(=6\sqrt{3}\)
\(B=\left(5-\dfrac{7-\sqrt{7}}{1-\sqrt{7}}\right)\left(\dfrac{\sqrt{14}+\sqrt{7}}{1+\sqrt{2}}-5\right)\)
\(=\left(5+\dfrac{\sqrt{7}\left(\sqrt{7}-1\right)}{\sqrt{7}-1}\right)\left(\dfrac{\sqrt{7}\left(\sqrt{2}+1\right)}{\sqrt{2}+1}-5\right)\)
\(=\left(\sqrt{7}-5\right)\left(\sqrt{7}+5\right)=7-25=-18\)
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