giúp tôi với ạ

Câu 14: $-15(\sqrt{22}+7\sqrt{2})\sqrt{30}-7\sqrt{11}$ $= -15\sqrt{22}\sqrt{30} - 15 \cdot 7\sqrt{2}\sqrt{30} - 7\sqrt{11}$ $= -15\sqrt{660} - 105\sqrt{60} - 7\sqrt{11}$ $= -15\sqrt{4 \cdot 165} - 105\sqrt{4 \cdot 15} - 7\sqrt{11}$ $= -15 \cdot 2\sqrt{165} - 105 \cdot 2\sqrt{15} - 7\sqrt{11}$ $= -30\sqrt{165} - 210\sqrt{15} - 7\sqrt{11}$ Câu 15: $A = (\sqrt{5} - 2)(\sqrt{5} + 2) - \frac{\sqrt{7 - 4\sqrt{3}}}{\sqrt{3} - 2}$ $= (\sqrt{5})^2 - 2^2 - \frac{\sqrt{7 - 4\sqrt{3}}}{\sqrt{3} - 2}$ $= 5 - 4 - \frac{\sqrt{7 - 4\sqrt{3}}}{\sqrt{3} - 2}$ $= 1 - \frac{\sqrt{7 - 4\sqrt{3}}}{\sqrt{3} - 2}$ $= 1 - \frac{\sqrt{(2 - \sqrt{3})^2}}{\sqrt{3} - 2}$ $= 1 - \frac{|2 - \sqrt{3}|}{\sqrt{3} - 2}$ $= 1 - \frac{2 - \sqrt{3}}{\sqrt{3} - 2}$ $= 1 - (-1)$ $= 1 + 1$ $= 2$ Câu 16: $A = (2 + 3\sqrt{2})^2 - \sqrt{288}$ $= 2^2 + 2 \cdot 2 \cdot 3\sqrt{2} + (3\sqrt{2})^2 - \sqrt{144 \cdot 2}$ $= 4 + 12\sqrt{2} + 9 \cdot 2 - 12\sqrt{2}$ $= 4 + 12\sqrt{2} + 18 - 12\sqrt{2}$ $= 22$ Câu 17: $A = (\sqrt{8} - 3\sqrt{2} + 2\sqrt{5})(\sqrt{2} + 10\sqrt{0,2})$ $= (\sqrt{4 \cdot 2} - 3\sqrt{2} + 2\sqrt{5})(\sqrt{2} + 10\sqrt{\frac{1}{5}})$ $= (2\sqrt{2} - 3\sqrt{2} + 2\sqrt{5})(\sqrt{2} + 10 \cdot \frac{\sqrt{5}}{5})$ $= (-\sqrt{2} + 2\sqrt{5})(\sqrt{2} + 2\sqrt{5})$ $= (-\sqrt{2})^2 + (-\sqrt{2}) \cdot 2\sqrt{5} + 2\sqrt{5} \cdot \sqrt{2} + (2\sqrt{5})^2$ $= 2 - 2\sqrt{10} + 2\sqrt{10} + 4 \cdot 5$ $= 2 + 20$ $= 22$