\(a,=\left(2\sqrt{7}-2\sqrt{14}+\sqrt{7}\right).\sqrt{7}+14\sqrt{2}\\ =\left(3\sqrt{7}-2\sqrt{14}\right).\sqrt{7}+14\sqrt{2}\\ =21-14\sqrt{2}+14\sqrt{2}\\ =21\\ b,=\sqrt{9+2.3.\sqrt{2}+2}-\sqrt{9-2.3.\sqrt{2}+2}\\ =\sqrt{\left(3+\sqrt{2}\right)^2}-\sqrt{\left(3-\sqrt{2}\right)^2}\\ =\left|3+\sqrt{2}\right|-\left|3-\sqrt{2}\right|\\ =3+\sqrt{2}-3+\sqrt{2}\\ =2\sqrt{2}\\ c,=\left(75\sqrt{2}+50\sqrt{2}-45\sqrt{2}\right):\sqrt{10}\\ =80\sqrt{2}:\sqrt{10}=16\sqrt{5}\)
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