Rút gọn các biểu thức sau:
a) \(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)
b) \(\left(\sqrt{28}-2\sqrt{3}+\sqrt{7}\right)\sqrt{7}+\sqrt{84}\)
c) \(\left(\sqrt{6}+\sqrt{5}\right)^2-\sqrt{120}\)
d) \(\left(\dfrac{1}{2}-\sqrt{\dfrac{1}{2}}-\dfrac{3}{2}\sqrt{2}+\dfrac{4}{5}\sqrt{200}\right):\dfrac{1}{8}\)
giúp nha