Question

1. Khử mẫu của biểu thức lấy cân :
a) sqrt(7/100) 
b) sqrt(4/5)
c) sqrt(1/12)
d) sqrt(3/20)
e) sqrt(1/20)
g) sqrt(1/60)

Answer 1

a: \(\sqrt{\dfrac{7}{100}}=\dfrac{\sqrt{7}}{\sqrt{100}}=\dfrac{\sqrt{7}}{10}\)

b: \(\sqrt{\dfrac{4}{5}}=\sqrt{\dfrac{20}{25}}=\dfrac{\sqrt{20}}{5}=\dfrac{2\sqrt{5}}{5}\)

c: \(\sqrt{\dfrac{1}{12}}=\sqrt{\dfrac{3}{36}}=\dfrac{\sqrt{3}}{6}\)

d: \(\sqrt{\dfrac{3}{20}}=\dfrac{\sqrt{3}}{2\sqrt{5}}=\dfrac{\sqrt{3}\cdot\sqrt{5}}{2\sqrt{5}\cdot\sqrt{5}}=\dfrac{\sqrt{15}}{10}\)

e: \(\sqrt{\dfrac{1}{20}}=\dfrac{1}{\sqrt{20}}=\dfrac{1}{2\sqrt{5}}=\dfrac{\sqrt{5}}{2\sqrt{5}\cdot\sqrt{5}}=\dfrac{\sqrt{5}}{10}\)

g: \(\sqrt{\dfrac{1}{60}}=\dfrac{1}{\sqrt{60}}=\dfrac{1}{2\sqrt{15}}=\dfrac{\sqrt{15}}{2\cdot15}=\dfrac{\sqrt{15}}{30}\)