Question

B 5.Tính giá trị của các biểu thức:

a) (\(\sqrt{12}\)-2\(\sqrt{108}\)+3\(\sqrt{75}\)).\(\sqrt{3}\)                     b)(3\(\sqrt{8}\)- 4\(\sqrt{32}\)+5\(\sqrt{18}\)):5

c)(\(\sqrt{20}\)-2\(\sqrt{45}\)+3\(\sqrt{125}\) ):\(\sqrt{5}\)                     d)(3\(\sqrt{7}\)-4\(\sqrt{28}\)+5\(\sqrt{343}\)).\(\dfrac{1}{10}\)

Answer 1

a: \(=\left(2\sqrt{3}-12\sqrt{3}+15\sqrt{3}\right)\cdot\sqrt{3}=5\sqrt{3}\cdot\sqrt{3}=15\)

b: \(=\left(6\sqrt{2}-16\sqrt{2}+15\sqrt{2}\right):5=\sqrt{2}\)

c: \(=\dfrac{\left(2\sqrt{5}-6\sqrt{5}+15\sqrt{5}\right)}{\sqrt{5}}=17-6=11\)