RÚT GỌN CÁC BIỂU THỨC SAU :
a ] \(\dfrac{1}{4}\)\(\sqrt{180}\) + \(\sqrt{20}\)- \(\sqrt{45}\) + 5
b] \(\sqrt[3]{\dfrac{1}{3}}\) +\(\dfrac{1}{4}\)\(\sqrt{48}\) - \(2\sqrt{3}\)
c] \(\sqrt{2a}\) - \(\sqrt{18}a^3\) +\(\sqrt[4]{\dfrac{a}{2}}\)
d]\(\sqrt{\dfrac{a}{1+2b+b^2}}\) . \(\sqrt{\dfrac{4a+8ab+4ab^2}{225}}\)